Patent Publication Number: US-2020282733-A1

Title: Print Liquid Supply

Description:
BACKGROUND 
     Print liquid supplies include reservoirs with print liquid. The print liquid can be a print agent such as ink or any agent to aid in the process of two-dimensional (2D) or three-dimensional (3D) printing. In use, the print liquid is to be provided to a print liquid dispense mechanism downstream of the supply. The print liquid dispense mechanism can be part of a larger 2D or 3D print system. The print system may include a plurality of receiving stations to allow different liquid type supplies to connect to the print liquid dispense mechanism and be replaced. Other print systems such as monochrome systems include only a single receiving station. 
    
    
     
       DRAWINGS 
         FIG. 1  illustrates a diagrammatic side view of an example of a liquid supply apparatus. 
         FIG. 2  illustrates a diagrammatic front view of the example liquid supply apparatus of  FIG. 1 . 
         FIG. 3  illustrates a diagram of a side view of a portion of an example print liquid supply apparatus. 
         FIG. 4  illustrates a diagram of a top view of a similar example of a liquid supply apparatus. 
         FIG. 5  illustrates a perspective view of a plurality of examples of liquid supply apparatuses and corresponding receiving stations. 
         FIG. 6  illustrates another perspective view of a plurality of examples of liquid supply apparatuses and corresponding receiving stations. 
         FIG. 7  illustrates a side view of an example of a receiving station having a liquid supply apparatus installed. 
         FIG. 8  illustrates a side view of an example of a liquid supply apparatus. 
         FIG. 9  illustrates a front view of the example liquid supply apparatus of  FIG. 8 . 
         FIG. 10  illustrates a diagram of an example of a front push area and liquid interface of an interface structure. 
         FIG. 11  illustrates a cross sectional top view on an example of an interface structure and receiving station, before or after fluidic connection. 
         FIG. 12  illustrates a cross sectional top view on an example of an interface structure and receiving station, during fluidic connection. 
         FIG. 13  illustrates a perspective view on an example of an interface structure projecting from a side of a container. 
         FIG. 14  illustrates a front view on an example of an interface structure. 
         FIG. 15  illustrates a perspective, detailed view on an example guide slot of the interface structure of  FIG. 14 . 
         FIG. 16  illustrates a side view of a detail of the example interface structure of some of the previous figures. 
         FIG. 17  illustrates a perspective view of an example of a liquid supply apparatus pushed into a receiving station. 
         FIGS. 17A and 17B  illustrate diagrams examples of respective guide features of interface structures. 
         FIG. 18  illustrates a cross sectional top view of an example illustrating an example hook and an example secure feature of a receiving station and interface structure, respectively. 
         FIG. 19  illustrates another perspective view of an example of an interface structure projecting from a container side. 
         FIG. 20  illustrates a perspective view on an example receiving station. 
         FIG. 21  illustrates a cross sectional top view on an example interface structure and receiving station in fluidically connected state. 
         FIG. 22  illustrates a cross sectional perspective view of an example liquid supply apparatus. 
         FIG. 23  illustrates a diagram illustrating an example liquid channel and its liquid flow path. 
         FIG. 24  illustrates a cross sectional top view of an example interface structure. 
         FIG. 25  illustrates a front view of the example interface structure of  FIG. 24 . 
         FIG. 26  illustrates a perspective view on an example interface structure. 
         FIG. 27  illustrates a perspective view on an example key pen. 
         FIG. 28  illustrates a cross sectional perspective view on an example liquid supply apparatus. 
         FIGS. 29-32  illustrate front views of an example key pen in different rotational orientations. 
         FIG. 33  illustrates a diagram of an example of a base hole in a base wall. 
         FIG. 34  illustrates a diagram of a cross section of an example key pen base portion. 
         FIG. 35  illustrates a front view of an example key pen. 
         FIG. 36  illustrates a diagram of a cross sectional front view of another example key pen. 
         FIG. 37  illustrates a diagram of a side view of an example of a key pen. 
         FIG. 37A  illustrates a diagram of a side view of another example key pen. 
         FIG. 38  illustrates a diagram of a front view of another example key pen. 
         FIG. 39  illustrates a diagram of a side view of another example key pen. 
         FIG. 40  illustrates an exploded view including an example kit  100  of components for construing a supply apparatus. 
         FIG. 40A  illustrates a diagram of an example unfilled reservoir. 
         FIG. 41  illustrates a perspective view of an example liquid supply apparatus. 
         FIG. 42  illustrates a front view of an example liquid supply apparatus. 
         FIG. 43  illustrates a perspective view of another example liquid supply apparatus. 
         FIG. 44  illustrates a diagram of a side view of another example liquid supply apparatus. 
         FIG. 45  illustrates a diagram of a side view of yet another example liquid supply apparatus. 
         FIG. 46  illustrates a perspective view of a plurality of example liquid supply apparatuses. 
         FIG. 47  illustrates a perspective view of an example receiving station and liquid supply apparatus. 
         FIG. 48  illustrates a diagram of a front and side view, left and right, respectively, of another example interface structure. 
         FIG. 49  illustrates a diagram of a front view of another example liquid supply apparatus. 
         FIG. 50  illustrates a diagram of a front view of yet another example liquid supply apparatus. 
         FIG. 50A  illustrates a diagram of a front view of again another example liquid supply apparatus. 
         FIG. 50B  illustrates a diagram of a front view of again another example liquid supply apparatus. 
         FIG. 50C  illustrates a diagram of a front view of again another example liquid supply apparatus. 
         FIG. 51  illustrates a diagram of a cross sectional top view of examples of an interface structure and a key pen structure. 
         FIG. 52  illustrates a diagram of a front view of again another example liquid supply apparatus. 
         FIG. 53  illustrates a diagram of a side view of the example liquid supply apparatus of  FIG. 52 . 
         FIG. 54  illustrates a diagram of a side view of again another example liquid supply apparatus. 
         FIG. 55  illustrates a diagram of a front view of the example liquid supply apparatus of  FIG. 54 . 
         FIG. 56  illustrates a perspective view of again another example liquid supply apparatus in partially disassembled state. 
         FIG. 57  illustrates another perspective view of the example liquid supply apparatus of  FIG. 56  in assembled state. 
         FIG. 58  illustrates a perspective view of again another example liquid supply apparatus. 
         FIG. 59  illustrates again a perspective view of the example liquid supply apparatus of  FIG. 58  being installed into a corresponding receiving station. 
         FIG. 60  illustrates a diagram of a front view of yet another example liquid supply apparatus. 
     
    
    
     DESCRIPTION 
     This disclosure addresses print liquid supply apparatuses, interface structures for use with print liquid supply apparatuses, and components of print liquid supply apparatuses and interface structures. In operation, an interface structure of this disclosure may be part of a replaceable print supply apparatus and may facilitate fluidically connecting the contents of the supply apparatus with a host apparatus, such as a printer. Example interface structures of this disclosure can be associated with a relatively wide range of different liquid volumes, supply types, and printer platforms, whereby printer platforms may be different in terms of operating with different media types, media formats, print speeds and/or liquid types, amongst others. 
     The liquid referred to in this disclosure may be a print liquid. The print liquid can be any type of agent for printing, including ink and 3D print agents and inhibitors. The print liquid may include certain amounts of gas and/or solids. While this disclosure mostly addresses print related aspects, it is recognized that the features and effects discussed in this disclosure could work for other types of liquid supply apparatuses for connection, with other types of host apparatuses. 
     For example, the print liquid supply apparatus of this disclosure can be associated with relatively high speed or large format print systems. The liquid reservoir volume of the supply apparatus may be at least approximately 50 ml (milliliters), at least approximately 90 ml, at least approximately 100 ml, at least approximately 200 ml, at least approximately 250 ml, at least approximately 400 ml, at least approximately 500 ml, at least approximately 700 ml or at least approximately 1 L (liter). In further examples, the supply apparatus may be adapted to contain larger liquid volumes, such as at least 1 L, at least 2 L, or at least 5 L. The reservoir volume of the supply apparatus of this disclosure may be scaled within a broad range of volumes. The same interface structure and the same receiving station may be associated with that broad range of volumes. The supply of this disclosure can facilitate using similar receiving station components for different print system platforms. For example, both smaller format and larger format printers, or both 2D and 3D printers, may be equipped with a similar receiving station to interface with the interface structures of this disclosure. This may lead to increased customization over a relatively wide product range which in turn may allow for cost control, efficiency, etc. 
     Further example interface structures and supply apparatuses of this disclosure facilitate a relatively easy mounting and unmounting of the supply apparatus with respect to the receiving station, irrespective of the internal liquid volume. In again further examples, relatively eco-friendly supply apparatuses are provided. 
     In this disclosure “approximately” or “at least approximately” should be understood as including some appropriate margin as well as “exactly”. For example, when referring to approximately 23 mm (millimeter) this may include a certain margin such as for example 0.5 mm more than or less than 23 mm, but it should also include exactly 23 mm. 
     In this disclosure certain examples are described with reference to the drawings. While the drawings illustrate certain combinations of features, also sub-combinations of features that are not illustrated in isolation can be derived from these drawings. Where helpful reference is made to certain sub-combinations of features, margins, ranges, alternatives, different features, and/or omission or addition of certain features, whereby the drawings may be used for reference purposes. 
       FIGS. 1 and 2  illustrate diagrams of a side and front view, respectively, of an example of a print liquid supply apparatus  1 . The print liquid supply apparatus  1  comprises a container  3  to hold print liquid. In one example the container  3  includes an at least partially collapsible reservoir to hold the liquid. In a further example the container  3  includes a support structure such as a box or tray at least partially around the reservoir to support and/or protect the reservoir. In this disclosure, without referring to a further reservoir or support structure, the container includes at least a reservoir. 
     In a filled state, the container  3  may have a substantially cuboid outer shape with rectangular outer walls and sharp or rounded edges that connect the walls. The container  3  can have other shapes. In an example the container  3  includes a collapsible bag adapted to collapse to facilitate withdrawal of the liquid. In the illustrated diagram the container  3  is illustrated in an expanded, for example filled, state. In an example, the container  3  is void of separate liquid retaining material such as foam. The container  3  may allow print liquid to freely move inside its liquid retaining volume. 
     The supply apparatus  1  includes an interface structure  5  for example to provide for a liquid connection between an internal liquid volume of the container  3  and a further host apparatus such as a printer. The interface structure  5  includes at least a liquid throughput  11  supplies liquid from the container  3  to a receiving station. As will be explained later in some examples liquid may during certain instances in time be provided back to the container  3 , for example due to certain pressure changes, or to mix or circulate liquid in the container  3 , either through a single liquid throughput channel or through multiple throughput channels of the same interface structure  3 . 
     In one example, a host apparatus such as a 2D or 3D printer includes a receiving station  7  to receive the interface structure  5 . The receiving station  7  may be a fixed or exchangeable part of the host apparatus. The diagram of  FIG. 1  illustrates a portion of a receiving station  7  including a liquid needle  9 . In this disclosure a liquid needle  9  may include any fluidic needle or pen for insertion into a fluidic interface of the supply apparatus. For example, the fluidic needle may include a metal or plastic needle. In other examples other types of receiving stations may be used, having liquid interfaces other than needles. Other types of fluidic interfaces of a receiving station may include towers, septums for receiving supply-side needles. The liquid throughput  11  is adapted to connect to the printer-side liquid interface. The example supply apparatus  1  is to be installed and removed with respect to the receiving station  7 . The interface structure  5  is adapted for mounting and unmounting with respect to the receiving station  7 . In one example the interface structure  5  is adapted for relatively user-friendly insertion and ejection with respect to the receiving station  7 . 
     The interface structure  5  may include a plurality of interface features that interact with the receiving station. As will be explained with reference to different examples and figures, the interface features may include the liquid interface  15 , data processing features, data connection features, guidance and alignment features, actuating features to mechanically actuate upon receiving station components, secure features, key features, etc. In certain examples the interface structure  5  may include a single molded structure at least part of which connects to, and projects from, the container  3 . The interface structure  5  may also serve as a separate cap for the container  3 , to seal the container  3  during transport and storage, after filling the container  3  with liquid before transport. 
     The container  3  and interface structure  5  each have respective first dimensions D 1 , d 1 , second dimensions D 2 , d 2  and third dimensions D 3 , d 3  that extend parallel to perpendicular reference axes y, x, z, respectively. In this disclosure the container dimensions D 1 , D 2 , D 3  represent (i) axes parallel to the respective reference axes y, x, z along which the container  3  extends, and (ii) extents of a container volume along said axes. In this disclosure the interface dimensions d 1 , d 2 , d 3  represent (i) axes parallel to the respective reference axes y, x, z, and (ii) extents of an interface profile of the interface structure  5  along said axes, wherein the interface profile is the portion of the interface structure  5  which is to interface with the receiving station. It may be understood that the interface profile, or first dimension d 1 , of the interface structure  5  spans interface components of the interface structure  5  that are to interface with the receiving station  7 . The interface structure may include elements that project outside of the interface dimensions d 1 , d 2 , d 3 , external to said interface profile, for example to connect to and/or support the container  3 . Each one of the first dimensions D 1 , d 1 , second dimensions D 2 , d 2  and third dimensions D 3 , d 3  may refer to a respective one of a height, length and width, depending on the orientation of the container  3  or interface structure  5 . 
     In the illustrated example of  FIGS. 1 and 2  the first dimension D 1 , d 1  represents a height, the second dimension D 2 , d 2  represents a length and the third dimension D 3 , d 3  represents a width of each of the container  3  and the interface structure  5 , respectively. As a skilled person will understand, in different instances and situations, the receiving station  7  and supply apparatus  1  may have different configurations and orientations and that is why this disclosure refers to “dimensions” or certain parallel “directions” or “axes” when describing certain features and their relative positions, dimensions and orientations. 
     On the other hand, for reasons of clarity this disclosure sometimes also uses more orientation-dependent language such as “top view”, “side view”, “front view”, “back”, “bottom”, “front”, “top”, “lateral side”, “width”, “height”, “length”, “lateral”, “distal”, etc. but this should be interpreted as intended for clarity only rather than limiting respective features to a particular orientation, unless explained otherwise. To illustrate this point, certain liquid supply apparatuses with a collapsing bag type reservoir may operate in any orientation, due to the nature of collapsing bag type reservoirs, whereby the interface structure may protrude from the container in any direction. Correspondingly, a projecting portion of the container may project in any direction, and the interface structure could project in any direction. Also, a “container bottom” may be oriented at the top of a container if that container is placed or mounted upside down as compared to some of the illustrations in this disclosure while this does not affect the functioning of the supply apparatus or interface structure. Also, a front of the interface structure or container may be oriented downwards in installed condition if the container is rotated 90 degrees with respect to the horizontal orientation that is illustrated in most of the figures. 
     Furthermore, the description may refer to virtual reference planes, virtual planes or planes which are meant to serve as a reference for explaining certain shapes, relative positions, dimensions, extents, orientations, etc. similar to the earlier explained axes, directions and dimensions d 1 , D 1 , d 2 , D 2 , d 3 , D 3 . 
     The interface structure  5  projects along the direction of the first dimension D 1 , d 1  outwards from the container  3 . In the illustration, the interface structure  5  protrudes from a container side  13  parallel to the second and third container dimension D 2 , D 3 . In the illustrated example the interface structure  5  protrudes from a bottom  13  of the container  3 , defined by a bottom wall. 
     In other examples, the interface structure  5  may protrude from one of a lateral side, front, back or top of the container  3 . In different examples the supply apparatus  1  may have different orientations in printer-installed or stored condition whereby the interface structure  5  may protrude in any direction, downwards, upwards, sideways, etc., and the first dimension D 1 , d 1  may be the corresponding direction. 
     The illustrated interface structure  5  projects outwards with respect to the outer wall  13  of the container  3  along a direction of the first dimension D 1 , d 1  so that a total first dimension D 1 +d 1  of the supply apparatus  1  can be approximately the sum of the two first dimensions D 1 , d 1  of the container  3  and the interface structure  5 . The first dimension D 1  of the container  3  may be the distance between opposite walls along that first dimension D 1 . The first dimension d 1  of the interface structure  5  may be the distance between opposite sides of the projecting portion of the interface structure  5  along said first dimensions d 1 . In certain examples, the interface structure  5  is of relatively low profile with multiple interface components extending within the relatively low profile. The first interface dimension d 1  may be less than half of the first container dimension D 1 , or less than a third, fourth, fifth, or sixth of the first container dimension D 1 . 
     The interface structure  5  includes a liquid throughput  11  to fluidically connect the container to the receiving station. The liquid throughput  11  further includes a liquid channel  17  fluidically connecting the inner volume of the container  3  with the receiving station  7  in installed condition. The liquid channel  17  includes a liquid interface  15  to fluidically interface with a counterpart liquid input interface of the receiving station  7 , embodied by a fluid needle  9  in the example of  FIG. 1 . In one example the liquid interface  15  includes a seal to receive, and seal to, the fluid needle  9 . The liquid channel  17  may be defined by at least one liquid channel wall, for example a cylindrical or otherwise rounded channel wall that extends around and along at least one central axis C 21  and/or C 29 . The liquid channel  17  may include a needle receiving channel portion  21  and a reservoir connecting channel portion  29 , for example with a curved intermediate liquid channel portion  19  in between. 
     The needle receiving channel portion  21  extends along a needle insertion direction NI and a main liquid flow direction DL opposite to the needle insertion direction NI. Central axis C 21  of the needle receiving channel portion  21 , interface  15  and seal extend along a needle insertion direction NI and a main liquid flow direction DL opposite to the needle insertion direction NI. The central axis C 21  of the needle receiving portion  21  may be relatively straight along the needle insertion direction NI to facilitate insertion of the needle  9 . In the drawing, the central axis C 21 , main liquid flow direction DL and needle insertion direction NI extend in a line. 
     The reservoir connecting liquid channel portion  29  may extend approximately parallel to the first interface dimension d 1 , or to a projection direction of the interface structure  5 , as indicated by the central axis C 29  of the reservoir connecting liquid channel portion  29 . The central axes C 21 , C 29  of the needle receiving channel portion  21  and the reservoir connecting channel portion  29  extend at an angle with respect to each other, for example an approximately straight angle. 
     The liquid channel  17  may further include an intermediate channel portion  19  between the needle receiving and reservoir connecting channel portions  21 ,  29 . The intermediate portion  19  may inflect the channel  17  between the needle receiving portion  21  and the reservoir connecting channel portion  29 , for example in a curved fashion, to connect the liquid interface  15  to the inner volume of the container  3 . The intermediate portion  19  may facilitate a curve and an offset between the needle receiving liquid channel portion  21  and the reservoir connecting liquid channel portion  29 . 
     The liquid channel  17  and interface  15 , including the seal  20  and needle receiving channel portion  21 , are adapted to facilitate the illustrated main liquid flow direction DL out of the interface structure  5  and needle insertion direction NI into the interface structure  5 . A main liquid flow direction DL of the needle receiving liquid channel portion  17  and the liquid interface  15  may extend straight out of the interface front  54 , for example parallel to the second interface dimension d 2  and/or second container dimension D 2 . The needle insertion direction NI may extend straight into the interface front  54 , for example parallel to the second interface dimension d 2  and/or second container dimension D 2 . It will be understood that, in a dismounted on-the-shelve condition of the supply apparatus  1  the main liquid flow direction DL and needle insertion direction NI can be defined by a central axis of the needle receiving liquid channel portion  21 , which in turn may be defined by internal walls of the needle receiving liquid channel  21  and/or by a internal walls or a center channel inside the seal  20 . In an example where there is a clearly definable central axis C 21  of the needle receiving liquid channel  21  and/or liquid interface  15  including seal  20 , that central axis C 21  may define the main liquid flow direction DL and needle insertion direction NI. The main liquid flow direction DL may be relatively straight as determined by a central axis and/or internal liquid channel walls of the seal  20  and/or needle receiving liquid channel portion  21  to facilitate straight entry of a corresponding fluid needle  9  along the respective second dimensions D 2 , d 2 . 
     The main liquid flow direction DL represents the course along which the liquid is to flow between from the container  3  to the receiving station, to print. In one example the liquid flows in one direction only, out of the liquid interface  15  to the receiving station  7 , at least most of the time. In other examples, the needle  9  and liquid channel  17  may be suitable for bi-directional flow, for example due to pressure fluctuations in the print system liquid circuit or for mixing/recirculating liquid in the container  3 . In fact, in some examples two liquid interfaces may be provided in the same supply apparatus, to interface with two corresponding fluid needles of a single receiving station to mix/recirculate the liquid in the container and/or print system liquid channels. An additional dotted circle is illustrated in  FIG. 2 , next to the liquid interface  15 , to illustrate this possibility. Hence, in this disclosure a main liquid flow direction DL refers to the liquid flowing out of the supply apparatus  1  to be able to print using that liquid, even if the flow in the liquid channel  17  may during certain time instances be in the opposite direction, either in the same liquid channel or in separate liquid channels. 
     In the illustrated example, a projecting portion  23  of the container  3  projects in a direction parallel to the main liquid flow direction DL surpassing the liquid interface  15  in the main liquid flow direction DL. Correspondingly, the projecting portion  23  projects in the second container dimension D 2 , whereby the second container dimension D 2  may be larger than the second interface dimension d 2 . The projecting portion  23  contains liquid so that in filled condition the liquid may be held above, or next to, and beyond the liquid interface  15 . In certain examples, more than one third or more than half of the second container dimensions D 2  may project beyond the liquid interface  15  in the main liquid flow direction DL. This may facilitate that the container projecting portion  23  can be inserted head first into a receiving station  7  before a sealed and operational connection between the receiving station  7  and the interface structure  5  is established. 
     In certain examples, the extent PP to which the projecting portion  23  of the container  3  surpasses the liquid interface  15  may determine the reservoir volume of the container  3 , whereby in a plurality of supply apparatuses  1  that have different volumes that connect to the same receiving station, the first and third dimensions d 1 , D 1 , d 3 , D 3  are the same but the second container dimension may vary. A relatively large liquid volume reservoir of the container  3  may be associated with a longer projecting portion  23 . 
     Some of these features may facilitate readily connecting a liquid volume size of choice to a receiving station  7 . By a ready push against a back  25  of the container  3 , in an insertion direction I parallel to the main liquid flow direction DL, the supply apparatus  1  can be pushed into a fluidically connected state with the receiving station  7 . In addition, a manufacturer can adapt the inner volume of the container  3  by scaling the projecting portion  23  while the ease of insertion of the supply apparatus  1  is the same because the back  25  and interface structure  5  are positioned the same between these different volumes. In certain examples, the projecting portion  23  protrudes into the receiving station  7  so that the back of the supply apparatus  1  does not protrude from the receiving station  7 , thereby preventing obstacles that operators could otherwise bump into. In the example of  FIG. 1  a back  25  of the container  3  extends a small distance Bb further than a back  26  of the interface structure  5 , as measured along the second container dimension D 2 . For example, such distance Bb may be between approximately 0 and 1 or between approximately 0 and 1 cm. 
     Where the projecting portion  23  projects beyond the liquid interface  15 , for example where the liquid volume is more than 100 ml, the interface structure  5  may be fluidically connected to the container  3  offset from a middle M of the second container dimension D 2  by an offset distance, for example of more than 5 mm or several cm (cm) depending on the liquid volume of the container  3 . Herein, the middle M may be defined by a virtual reference plane that is parallel to the first and third container dimension D 1 , D 3  and in the middle of the second container dimension D 2 . In the illustrated example, the middle M of the second container dimension D 2  extends in the middle between a front  31  and back  25  of the container  3 , and the reservoir connecting portion  29  of the liquid channel  17  connects to the internal reservoir volume of the container  3  behind the middle M, between the middle M and the back  25  of the container  3 . As illustrated, the reservoir connecting portion  29  of the liquid channel  17  of the interface structure  5  is connected to a liquid output  30  of the container  3  to facilitate throughput of liquid from the container  3  through the interface structure  5 . Correspondingly, the fluid connection between the container liquid output  30  and the reservoir connecting portion  29  of the liquid channel  17  is provided between the middle plane M and the back  25  of the container  3 . 
       FIG. 3  illustrates a diagram of a side view of an example of a print liquid supply apparatus  1  wherein the container  3  includes a bag-in-box type structure. In the illustrated state, a reservoir  33  is illustrated that is substantially empty and collapsed. The reservoir  33  has air and vapor barrier walls to inhibit vapor exiting and air entering the reservoir  33 . In the illustrated state, most or all liquid has been withdrawn from the reservoir  33  that has collapsed accordingly, in a relatively random fashion. In the illustrated example the reservoir  33  is a substantially completely flexible bag but in other examples the reservoir could have some rigid portions. The reservoir  33  may be rigid near the output  30  to facilitate connection with the interface structure  5 . 
     In an example the container  3  further includes a support structure  35  at least partially around the reservoir  33 , for example to support and protect the reservoir  33 . The support structure  35  may also to facilitate relatively rough guiding of the supply apparatus  1  into the receiving station  7 . In again other examples, the support structure  35  may facilitate stacking, storage, and presentation of usage, brand and contents information. In a filled state the reservoir  33  may occupy most of the inner volume of the support structure  35 . For example, the outer volume of the reservoir  33  in a filled state may be more than 60%, more than 70%, more than 80% or more than 90% of the inner volume of the support structure  35 . For example, the same reservoir  33  having a predefined volume capacity may be used for different support structures  35  of different volumes. For example, the reservoirs  33  may be filled partly or completely depending on the inner volume of the support structure  35 . For example, the reservoir  33  can be filled with less than 90%, less than 80%, less than 70%, less than 60%, less than 50%, less than 40% or even lower percentages of its maximum volume capacity. For example, while a reservoir  33  may have a maximum capacity of 2 L, that same 2 L reservoir may be only partially filled and seated in a support structure  35  having a maximum capacity of less than 2 L, such as 500 ml or 1 L, whereby a supply apparatus  1  of 500 ml or a supply apparatus  1  of 1 L is provided, respectively. 
     As can be seen from  FIG. 4 , which is diagrammatic top view on an example supply apparatus  1  along the first container dimension D 1  and interface structure projection direction, the interface structure  5  and its interface components may extend within an area or contour defined by an outer volume of the container  3 , for example as defined by the outer walls  25 ,  31 ,  51 . The illustrated outer walls  25 ,  31 ,  51  extend approximately parallel to the first container dimension D 1 , in the illustrated filled state of the container  3 . In the illustrated example, the second and third interface dimension d 2 , d 3  are less than the corresponding second and third container dimension D 2 , D 3 , whereby the second and third container dimension D 2 , D 3  overlap the second and third interface dimension d 2 , d 3  as seen in directions perpendicular to the respective second and third dimensions. 
     In an example the support structure  35  may be made of carton or other suitable material, such as for example other cellulose based material or plastics. In certain examples, the support structure material include corrugated cardboard and/or fiberboard. The support structure  35  may be relatively rigid as compared to the at least partially collapsible reservoir  33 , for example to provide support, protection and stack-ability to the reservoir  33 . The interface structure  5  is relatively rigid to facilitate relatively precise guiding with respect to the receiving station  7 , for example, more rigid than the support structure  35 . The interface structure  5  may include relatively rigid molded plastics. In one example liquid flow components of the reservoir  33  and interface structure  5  are relatively fluid impermeable, that is liquid, vapor and air impermeable, as compared to the support structure  35 . The impermeability of the interface structure  5  facilitates its capping function. The supply apparatus  1  may be opened by opening, removing, rupturing, etc., the seal of the interface structure. 
     In an example, the interface structure  5  includes at least one straight guide surface  41 ,  43  to slide the interface structure  5  along corresponding receiving station surfaces to facilitate installation of the container  3  in the receiving station  7 , as illustrated by  FIGS. 1 and 2 . The at least one straight guide surface  41 ,  43  may be elongate in the direction of, and extend approximately parallel to, the second dimension D 2 , d 2  of the interface structure  5  and the container  3 . The at least one straight guide surface  41 ,  43  may comprise opposite lateral guide surfaces  41  at external lateral sides or side walls  39 , each lateral guide surface extending approximately parallel to the first and second interface dimension d 1 , d 2 . The at least one straight guide surface  41 ,  43  may comprise an intermediate guide surface  43  at a distal side  37 , the intermediate guide surface extending opposite to the side  13  of the container  3  from which the interface structure  5  projects, and between the lateral sides  39 . In the illustrated example, the distal side  37  defines a bottom of the interface structure  5 . The intermediate guide surface  43  may be approximately parallel to the second and third interface dimension d 2 , d 3 . 
     The lateral and intermediate guide surfaces  41 ,  43  may be relatively flat. The lateral and intermediate guide surfaces  41 ,  43  may be relatively elongate along the direction of the second interface dimension d 2 , along at least a portion of the interface structure  5 , at least sufficiently elongate to facilitate confining the movement of the supply apparatus to the second interface dimension d 2  and positioning the liquid interface  15 . The guide surfaces  41 ,  43  of the interface structure  41 ,  43  may be defined by relatively flat, flush and elongate outer surfaces of the interface structure  5  to facilitate sliding in a direction along the second interface dimension d 2  and positioning of the liquid interface  15  in respective direction along the first and third interface dimension d 1 , d 3 . In one example the third interface dimension d 3  extends between the external lateral guide surfaces  41 . In one example, the second interface dimension d 2  may be defined by the length of the intermediate guide surface  43  from the front to the back of the interface structure  5 . 
     In this example, the lateral guide surfaces  41  are adapted to (i) guide the liquid interface  15  in a direction along the second interface dimension d 2  and the main liquid flow direction DL, and (ii) facilitate positioning of the liquid interface  15  along an axis parallel to the third interface dimension d 3  by limiting the degree of freedom of the interface structure  5  in the receiving station  7  in the opposite directions parallel to the third interface dimension d 3 . The intermediate guide surface  43  is adapted to (i) guide the liquid interface  15  in a direction along the second interface dimensions d 2  and the main liquid flow direction DL, and (ii) to facilitate positioning of the liquid interface  15  along an axis parallel to the first interface dimension d 1  by limiting the degree of freedom of the interface structure  5  in the receiving station  7  in at least one direction of the first interface dimension d 1 . In the example where during installation the interface structure  5  projects downwards from the bottom  13  the intermediate guide surface  43  may include a horizontal surface to facilitate vertical positioning of the liquid interface  15  with respect to the liquid input interface of the receiving station  7 , by sliding over a corresponding horizontal bottom guide surface of the receiving station. To that end the intermediate guide surface  43  may extend at a predetermined distance from a central axis CP 21  of the needle receiving liquid channel portion  21 . The intermediate guide surface  43  may span a substantial portion of the distal side  37  of the interface structure  5 , along the second and third interface dimensions d 2 , d 3 , whereby the first interface dimension d 1  may extend between the side  13  of the container  3  from which the interface structure  5  projects and the intermediate guide surface  43 . 
       FIGS. 5 and 6  illustrate perspective views of examples of sets of different volume print liquid supply apparatuses  101  and corresponding receiving stations  107 .  FIG. 7  illustrates any of these print supply apparatuses  101  installed in one of those receiving stations  107 .  FIGS. 8 and 9  illustrate a single, similar, example supply apparatus  101  in side and front view, respectively. Features, functions and definitions disclosed with reference to  FIGS. 1-4  may similarly apply to the examples explained with reference to  FIGS. 5-9 . 
     In one example, the volumes of the four supply apparatuses  101  of  FIGS. 5 and 6 , from the smaller to the larger supply apparatuses  101 , that is, from front to back in  FIG. 5  and from left to right in  FIG. 6 , are 100, 200, 500 and 1000 ml, respectively. The interface structures  105  of the different illustrated supply apparatuses  101  have approximately the same dimensions d 1 , d 2 , d 3  and some of the same interface components, except for certain differences such as for example key pen orientations and data stored on integrated circuits. The different volume supply apparatuses  101  have different container volumes, wherein the first and third container dimensions D 1  and D 3  are approximately the same, yet the second container dimensions D 2  are different. Each container  103  is associated with a different liquid volume capacity and a different projecting length PP of the projecting portions  123 . The illustrated example containers  103  include a box-shaped support structure  135  of folded carton or the like, and an inner collapsible reservoir. For example, the support structure  135  includes corrugated cardboard and/or fiberboard. Note that while the support structures  135  may provide for different volumes and second container dimensions D 2 , the reservoirs inside the support structures may be of the same design, as in having the same maximum capacity, but with different fill amounts, for example a fill amount approximately corresponding to the respective support structure volume. 
     In  FIGS. 5 and 6 , each interface structure  105  projects from the bottom  113  at an equal distance from the back  125  of the container  103 , for example relatively close to the back  125 . As illustrated in  FIG. 8  a distance between a back  126  of the interface structure  105  and the back  125  of the container  103  along the second dimension D 2 , d 2  of the container  103  and the interface structure  105 , as defined by the distance between virtual reference planes over said backs  125 ,  126  parallel to the first and third dimension D 1 , d 1 , D 3 , d 3 , can be approximately 0 mm, or for example less than 1 cm. As illustrated in  FIG. 8 , the backs  125 ,  126  of the container  103  and the interface structure  105  could be approximately flush with respect to each other. In other examples the back  125  of the container  103  may extend further backwards than the back  126  of the interface structure  105  whereby the distance can be slightly larger than 0 mm, such as 1-5 mm, or substantially larger than 0 mm, such as greater than 1 cm, see for example the diagrammatic examples of  FIGS. 44 and 45 . In another, different example the back  126  of the interface structure  105  could protrude from the container back  125  whereby again there may be a distance between said backs  125 ,  126  greater than 0 mm but in the opposite direction as explained before. 
     Each different volume supply apparatus  101  of  FIGS. 5 and 6  has a different container  103  with a different second container dimension D 2 , that is, a different length PP of the projecting portion  123  along the second container dimension D 2 , wherein the length PP of the projecting portion  123  may be defined by the extent in which the second container dimension D 2  projects beyond an edge  116  of a liquid interface  115  and/or interface front  154 , in the main liquid flow direction DL ( FIG. 8 ). 
     The smaller supply volumes, for example of 100 ml or less such as the front supply apparatus  101  of  FIG. 5  and the corresponding one in  FIG. 6 , may have a second container dimension D 2  of similar length as the second interface dimension d 2 , or even less, where there is no or hardly any projecting portion  123  that projects beyond the interface edge  116 , as indicated by reference number  123   b . Hence, the projecting length PP of the container  103  may be zero or is relatively small. Larger volumes, for example greater than 100 ml as illustrated by the other supply apparatuses of  FIG. 5  and the corresponding ones in  FIG. 6 , may have a second container dimension D 2  that is greater than the second interface dimension d 2 . In certain examples, the second container dimension can be at least two times or at least three times the second interface dimension d 2 . In these examples the extent PP of the projecting portion  123  is greater than the second interface dimension d 2 . These different container volumes and projection extents PP may be associated with substantially the same interface structures  105  and substantially the same receiving stations  107 . Also, the same reservoir bag capacity may be used for the different volumes and different support structures  135  but with different fill grades. 
     In a substantially horizontal orientation of the supply apparatus  101 , the interface structure  105  may protrude from the bottom  113  of the box, near a back  125  of the box, and the box projects over the interface structure  105  towards the front, beyond a liquid interface  115  of the liquid output, whereby for the different examples the projection extent PP determines the maximum liquid volume capacity of the container  103 . 
     The third interface dimension d 3  may be defined by the distance between the external lateral sides  139 , as defined by lateral side walls  139   a , and the third container dimension D 3  may be defined by the distance between outer surfaces of opposite lateral sides  151  of the container  103 . In the illustrated examples, the width of the supply apparatuses  101  is determined by the third container dimension D 3 . The width is relatively small, providing for a relatively thin aspect ratio of the supply apparatuses  101 , which in turn may facilitate a small foot print of the collection of receiving stations in a single printer, while being connectable to a relatively large supply volume range. In the illustrated examples, the third interface dimension d 3  is slightly less than the third container dimension D 3 . For example, the third interface dimension d 3  is approximately 80-100% of the third container dimension D 3 , for example approximately 85-100%, or for example approximately 90-100%. The third interface dimension d 3  may be between approximately 30 and 52 mm, for example between approximately 48 and 50 mm. Correspondingly the third container dimension D 3  may be greater such as between 30 and 65 mm, or between 45 mm and 63 mm, or between 50 and 63 mm. The third container dimension D 3  could be varied depending on the internal width of the receiving station  107  and/or the pitch between adjacent receiving stations  107 . In other examples the third container dimension D 3  could be substantially larger than the third interface dimension d 3  (see for example  FIG. 46 ). 
     One example effect of the container  103  projecting in the main liquid flow direction DL, beyond the liquid interface  115 , is that it facilitates consistent and relatively user-friendly mounting and unmounting of different supply apparatuses  101  of a relatively large range of volumes, including relatively large volumes. In the prior art, these large volume supplies can be relatively cumbersome to handle or install to the printer. In addition, printer OEMs sometimes have different supply designs to handle different liquid volumes for different platforms but in the present example, the supply apparatuses can be mounted and unmounted by a relatively simple push at the back  125 , in the direction of the main liquid flow direction DL. As illustrated in  FIG. 7 , the back  125  may extend approximately in line with the receiving opening edge of the receiving station, again facilitating a ready push to the back  125  into the receiving station to mount and unmount the supply apparatus  101 . Also, the liquid interface  115  is still relatively close to the back which may facilitate increased user control at installation, for positioning with respect to a liquid needle of the receiving station. Different, relatively long projection extents PP need not affect the robustness and ease of installation. In fact, in certain examples the projecting portion  123  may facilitate some pre-alignment of the supply apparatus  101  the receiving station  107 . 
     The supply apparatus  101  of the present example allows for a first rough alignment to the receiving station  107  when placing the projecting portion  123  of the container  103  in the receiving station  107 , and then a second, more precise alignment using the interface structure guide and/or key features, that may engage corresponding guide and/or key features of the receiving station, which will further align the liquid interfaces. Such stepped alignment may prevent damage to receiving station components such as the fluid needle, which could otherwise be easily damaged due to repetitive connection of heavy large volume supply apparatuses. 
     The extent of the projecting portion of the interface structure  105  is represented by the first interface dimension d 1 . In this example, the first interface dimension d 1  may be measured between said the container side  113  from which the interface structure  5  projects and an external or distal side  137  of the interface structure  105 , for example between proximal and distal front edges (e.g. respectively represented by  154   b  and  154   c  in  FIG. 10 ) of the interface structure  105  at opposite sides of the liquid interface  115 . In this example the external or distal side  137  is defined by a support wall  137   a  parallel to the second and third interface dimensions d 2 , d 3  that also includes the intermediate guide slot  144 . 
     The first interface dimension d 1  can be at least six times smaller than the first container dimension D 1 . In the illustrated orientation this corresponds to a projecting height of the interface structure  105  being at least six times less than the height of the container  103 . This provides for a relatively large liquid volume container  103  combined with a relatively low-profile interface structure  105 , facilitating further volumetric efficiency, for example for on-the-shelf storage and transport, as well as for the print system with the supply apparatus installed. Also, a relatively small low-profile interface structure  105  may be more suitable for relatively smaller liquid volumes and relatively smaller printers. For example, the first container dimension D 1  is at least 6 cm and the first interface dimension d 1  of the projecting portion of the interface structure  105  is 20 mm or less. For example, the first container dimension D 1  is at least 9 cm and the first interface dimension d 1  is 15 mm or less. For example, the first container dimension D 1  is at least approximately 9.5 cm and the first interface dimension d 1  is approximately 13 mm or less. 
     For example, the profile height of the interface structure  105  may be the first interface dimension d 1  and the distance over which the interface structure  105  projects from the respective container side  113 , when assembled to the container  103 . The low-profile height of the interface structure  105  may refer to a relatively small first dimension d 1  of the interface structure  105  and the interface structure representing a relatively small projection from the container  103 . The profile height may span several interface components including the needle receiving portion  121  (e.g. see  FIG. 11 ) of the liquid channel  117 , the liquid interface  105 , the key pens  165 , the integrated circuit  174 , and the edge  154   b  of a front push area  154   a . For example, also a secure feature  157  at an external lateral side of the respective key pen  165 , that includes at least one of a clearance  159  and stop surface  163 , may extend within the profile height, or first dimension d 1 , of the interface structure  105 . The reservoir connecting liquid channel portion  129  may project outside of the profile height, into the container  103  when assembled to the container  103 . There may be more projecting components of the interface structure  105  that project outside of the profile height, for example for attachment to the container, support to the receiving station, or for other purposes. 
     In an example the width (d 3 ) of the interface structure  105  may be approximately 49 mm and the width (D 3 ) of the container  103  may be approximately 58 mm. The height (d 1 ) of the interface structure  105  may be approximately 12 mm and the height (D 1 ) of the box may be approximately 10 cm. Hence, a total aspect ratio of the first dimensions D 1 +d 1  and third dimensions D 3  of the supply apparatus  101  may be 112:58, which could be rounded to approximately 2:1 or 11:6. The length (d 2 ) of the interface structure, perpendicular to said height and width, may be approximately 43 mm, and the length (D 2 ) of the box may be equal or more depending on said projection extent PP. 
     As said, example supply apparatuses  101  of this disclosure have a relatively thin aspect ratio. Hence, in one example the aspect ratio of the second container dimension D 2  versus the third container dimension D 3  is at least 1:2, at least 1:3 or at least 1:4, that is, the second container dimension D 2  can be at least two, three or four times greater than the third container dimension D 3  wherein the second container dimension D 2  may correspond to a length and the third container dimension D 3  may correspond to a width. 
     In one example an aspect ratio of the first dimension D 1  versus the third dimension D 3  of the container  103  is at least 3:2 or at least 5:3 or at least approximately 11:6. In a further example the aspect ratio of the total first dimension (or height) of the supply apparatus, which may be the sum of the first container dimension D 1  and the first interface dimension d 1 , versus the third dimension D 3  of the container  103  (or width of the supply apparatus) is at least approximately 2:1. In some of the larger volume supply apparatuses  101  with a similar thin aspect ratio the container  103  may have a relatively long shape whereby the aspect ratio of the first container dimension D 1  versus the second container dimension D 2  is 1:1 or less, or 2:3 or less, 1:2 or less, or 1:3 or less, whereby smaller ratios refer to smaller first dimensions D 1  relative to greater second dimensions D 2 . 
     As illustrated in  FIGS. 8 and 9  the interface structure  105  may project from a side  113  in a direction parallel to the first dimension D 1  of the container  103  wherein the interface dimensions d 2 , d 3  are smaller than the container dimensions D 2 , D 3  so that the interface structure  105  extends within a contour formed by the second and third container dimensions D 2 , D 3 , similar to the example of  FIG. 4 . 
     The liquid output of the interface structure  105  includes a liquid channel  117 . The liquid channel includes a liquid interface  115 . The liquid interface  115  is provided at the downstream end of the liquid channel  117  along a main direction of flow. In  FIG. 9  a center plane CP of the container  103  and interface structure  105  is illustrated, that may serve as a virtual reference plane. The center plane CP may extend approximately through a middle of the third dimension D 3 , d 3  of the container  103  and/or interface structure  105 . The center plane CP extends parallel to the first and second dimensions D 1 , d 1 , D 2 , d 2 , of the container  103  and interface structure  105 , whereby the liquid interface  115  is laterally offset from the center plane CP of the interface structure  105  in one direction along the third interface dimension d 3 . Integrated circuit contact pads  175  are laterally offset from the center plane CP in the other direction along the third interface dimension d 3 , which is the opposite side of the center plane CP with respect to the liquid interface  115 . Note that, in other examples a plane parallel to the first and second dimensions D 1 , d 1 , D 2 , d 2 , and between the liquid interface  115  and contact pad array  175 , need not be exactly through the center of the supply apparatus. 
     In an example, a first recess  171   a  is provided laterally next to the needle receiving liquid channel portion  121  and houses a key pen  165 , and a second recess  171   b  is provided at the other lateral side of the needle receiving liquid channel portion  121  and houses another key pen  165  and the integrated circuit contact pads  175 . The recesses  171   a ,  171   b  may have entrances at each lateral side of the liquid interface  115  and interface structure front surface  154 , whereby the front surface  154  may be part of a liquid channel block extending between the recesses  171   a ,  171   b , through which the liquid channel  117  extends. The recesses  171   a ,  171   b  have a depth along the container side  113  from which the interface structure  105  projects. The key pens  165  protrude parallel to the second interface dimension d 2 . 
       FIGS. 10, 11 and 12  illustrate interface components of the interface structure according to certain examples.  FIG. 10  is a diagrammatic amplification of an example liquid interface  115  and a front push area  154   b  of an interface structure front  154  as also illustrated in  FIG. 9 , and  FIGS. 11 and 12  illustrate cross sectional top views of portions of the interface structure  105  and receiving station  107 , in a disconnected and connected stage of interface components, respectively. 
     In an example the liquid interface  115  includes a seal  120  to seal the channel  117  around a fluid needle at insertion. The seal  120  may be of elastomer material. The seal  120  may include a central internal channel along its central axis and along the needle insertion direction NI, through which the needle protrudes in installed condition. The seal  120  can be a plug to be plugged into internal walls of the liquid interface  115  and needle receiving liquid channel portion  121 , to extend along a length of the interface  115  and channel portion  121 . The seal  120  may sit in a cylindrical or round fitting in an interface front  154  of the interface structure  105 . The seal  120  may be sealed with respect to the liquid channel  117  and interface edge  116  by swaging. For example, during manufacture, a seal plug or other seal  120  is inserted into the liquid channel  117  after which a protruding ridge  118  of the edge  116  is pushed into a mushroom-like profile by an ultrasonically vibrating tool. The inner edge of the lip of the profile then retains the seal  120  and may also provide pressure to the seal  120  to obtain sufficient fluid tightness. In addition, or instead, adhesive and/or welding may be applied for establishing a proper seal structure in the interface structure  105 . 
     The seal  120  may include a breakable membrane  122  at its center, for example downstream of its central internal channel, that is configured to open when a needle is inserted for the first time. The needle may pierce the membrane  122  at insertion. The needle receiving liquid channel portion  121 , seal  120 , membrane  122 , and edge  116  may be centered around a single central axis, which for the purpose of illustration can be indicated in  FIG. 8  by main liquid flow direction DL. The depth of the seal  120  extends along that central axis and the seal  120  is adapted to seal to the inserted needle, along said central axis. In certain instances, the seal  120  may, in use, push a humidor  112  of the fluid needle. The seal  120  and membrane  122  inhibit fluid/vapor transfer to seal the container  103  during transport or on the shelf life of the supply apparatus  101 , as well as seal to the needle during needle insertion. Instead of a pierceable membrane  122 , the seal  120  could also include any suitable plug, label, membrane or film or the like, adhered, welded, attached or integrally molded to the seal  120 , for example for tearing, removing or piercing, that covers the internal channel of the seal  120  at the downstream end for sealing the container and liquid channel before usage. A separate lid or plug could be provided, or other measures, to seal the liquid channel  117  during transport and storage. 
     In this example, an edge  116  of the liquid interface  115  extends around the seal  120 . The seal  120  is inserted in the liquid interface  115  and needle receiving channel portion  121  of the liquid channel  117 . The seal  120  may partly lie against said edge  116 . The edge  116  may be round and extend around a central axis of a similarly round needle receiving channel portion  121  and seal  120 . The edge  116  may be part of the front  154  of the interface structure adjacent and around the liquid interface  115 . In one example the edge  116  may be flush with the rest of the front  154  while in other examples the edge  116  may include a protruding ridge  118 , before or after manufacture. In the example illustrated in  FIGS. 9-12 , the ridge  118  represents a state before swaging wherein the ridge  118  protrudes sufficiently to be swaged against and/or around the seal  120 , whereby the ridge  118  relatively flatter after said swaging, which is not illustrated in this drawing. 
     The interface front  154  and/or edge  116  may form an extreme of the second interface dimension d 2 . Front edges of walls  139   a ,  137   a  that define the respective lateral sides  139  and/or distal side  137  may extend at the same level as the interface front  154 , forming a circumferential interface front edge, that may serve as respective entrances to the recesses  171   a ,  171   b . The interface front  154 , adjacent and/or partially around the interface edge  116  may, in use, push against a protective structure  110  of the needle. In different examples a protective structure of the needle may include a shutter, plate, sleeve, sled or the like. 
     The illustrated example protective structure  110  includes a plate or sleeve to protect the fluid needle against mechanical damage, and may be retracted with respect to the needle by a pushing force of the interface front  154  against the protective structure when inserting the supply apparatus  101 . In the illustrated example the protective structure  110  that protects the needle is separate from the humidor  112  whereby the protective structure  110  may be moved by the interface front  154 , for example a push area  154   a  of the front  154 , and the humidor  112  can be moved separately by the protective structure  110  and/or the interface  115 . The humidor  112  may be adapted to keep the liquid needle wet and/or avoid leaking. In other example receiving stations the protective structure  110  and humidor  112  could be moved together as a single connected structure. In again other example receiving stations only one of a protective structure  110  and humidor  112  is provided. The front push area  154   a  can be used to push against the humidor  112  in addition to, or instead of the protective structure  110 , to release the needle  109 . 
     In the illustrated example, the interface front  154  extends between the recesses  171   a ,  171   b . A distal edge  154   c  of the front extends further out towards the lateral sides to define the entrance of the recesses  171   a ,  171   b , between the interface front  154  and the lateral sides  139 . The interface front  154  extends at least partially around, and adjacent to, the liquid interface  115 . The interface front  154  may be a straight surface at an approximately straight angle with the main liquid flow direction DL, parallel to the first and third interface dimension d 1 , d 3 . 
     The interface front  154  includes a push area  154   a , which may be defined by a wall portion located between the liquid interface edge  116  and the container  103 , at least when the interface structure  105  is assembled to the container  103 . The wall portion that defines the front push area  154   a  may be part of a structure that is integrally molded with the liquid channel wall  117   b , that protrudes from the support wall  137   a  with the recesses  171   a ,  171   b  on either side (e.g. see  FIG. 26 ). The push area  154   a  includes and terminates on an outer edge  154   b  of the front  154  of the interface structure  105 , that in the illustrated example terminates on the container side  113 . The push area  154   a  is adapted to force the protective structure  110  backwards during insertion and/or in installed condition. The push area  154   a  may extend at least partially between the liquid interface edge  116  and the container  103 . In certain examples indents, channels or recesses could be provided between the liquid interface edge  116  and the push area edge  154   b , into the front  154 , whereby the push area  154   a  may consist of only the edge  154   b , which may be sufficient to serve as the push area to abut the protective structure  110  (e.g. see  FIG. 48 ). 
     The interface structure  105  may be of relatively low profile. Hence, in one example a height HC of the push area  154   a , along the first interface dimension d 1 , wherein said height HC represents a smallest distance between the liquid interface edge  116  and the container  103  or interface front edge  154   b , is less than the inner diameter D 116  of the liquid interface edge  116 , or less than the outer diameter of the seal  120  when plugged into the outlet interface  115 , for example the height HC is less than half of one of said diameters D 116 . Said inner and outer diameter may be the same so that any one or both of these diameters could serve as a reference to indicate the relatively small height of the push area  154   a  and in turn, the relatively low-profile height of the interface structure  105 . For clarity, the liquid interface edge  116  may be defined by the transition between (i) plastic walls of the needle receiving portion  121  of the liquid channel  117  and (ii) the surface of the interface front  154 . In some examples it may be difficult to determine what is exactly the liquid interface edge  116  because that edge may be rounded. In such examples the outer diameter of a plugged portion of the seal  120  in plugged condition, at a point near the interface front  154  but within the liquid channel  117 , may be used. For example, said height HC of the push area  154   a  between said edges  116 ,  154   b  is equal to or less than approximately 6 mm, equal to or less than approximately 5 mm, equal to or less than approximately 4 mm, or equal to or less than approximately 3 mm. For example, in a relative sense, the height HC of the interface front push area  154   a  may be less than half of the diameter of said liquid outlet interface edge  116 . A relatively small interface front push area  154   a  may be sufficient to move the protective structure with respect to the needle, while still facilitating a relatively low-profile interface structure. For example, the push area  154   a  need not be a flat front wall but could instead comprise only an edge (e.g. front edge  154   b ) or rounded shape, sufficient to push the protective structure  110  to release the needle. 
     In the example of  FIG. 11 , the interface front  154  initiates pushing the protective structure  110  backwards with respect to the needle  109  to expose the needle  109  to facilitate insertion of the needle  109  into the liquid interface  115 . For example, first the push area  154   a  of the interface front  154  pushes the protective structure  110 , and then the protective structure  110  itself, or the front  154  or seal  120  pushes the humidor  112 . The latter is illustrated in  FIG. 12 , wherein the interface structure  105  has moved in the direction of the liquid output DL as compared to the position of  FIG. 11 , whereby the protective structure  110  and humidor  112  have been moved backwards with respect to the needle  109  by the push area  154   a , thereby extracting the needle  109 . In  FIG. 12 , the needle  109  has pierced the seal membrane  122 , and a fluidic connection between the liquid channel  117  and the needle  109  has been established. 
     In one example, the distal side  137  spans the extent of the third interface dimension d 3 . A support wall  137   a  of the interface structure  105  may define the distal side  137 . The support wall  137   a  may be partly to guide and support the supply apparatus  101  in the receiving station, for example through its intermediate guide surfaces  143 ,  143   b ,  147 , which may form part of the support wall  137   a . A portion of the support wall  137   a  may support the integrated circuit  174 . A relatively shallow cut out may be provided in the support wall  137   a  to seat the integrated circuit  174 . For example, the shallow cut out may be less than 2 or less than 1 mm deep. The support wall  137   a  may have a distal front edge  154   c  opposite to the push area front edge  154   b , along the third interface dimension d 3 , the first interface dimension d 1  extending between these opposite front edges  154   b ,  154   c.    
     The view of  FIG. 11  exposes integrated circuit contact pads  175  laterally next to the liquid interface  115  and in a respective recess  171   b . The pads  175  are arranged on a line parallel to the third interface dimension d 3  and in a virtual reference plane parallel to the second and third interface dimension d 2 , d 3 . In an example, the contact pads  175  are arranged on one side of the center plane CP, while the liquid interface  115 , or the center axis of the liquid interface  115 , is arranged on the opposite side of the center plane CP. During connection, as illustrated by  FIG. 12 , a data connector  173  of the receiving station  107  passes into the recess  171   b  to connect to the integrated circuit contact pads  175 . 
       FIGS. 13 and 14  illustrate an example of an interface structure  105  protruding from a respective container  103 , in perspective and front view, respectively. The interface structure  105  may be the same as the interface structure  105  illustrated in one of  FIGS. 5-12 .  FIG. 15  illustrates an example of a detail of an intermediate guide of the interface structure  105  of  FIGS. 13 and 14 .  FIG. 16  illustrates and example of a detail of a lateral guide of the interface structure  105 , near a front side of the interface structure  105 , and a secure feature  157 . 
     In the examples illustrated in  FIGS. 13-16 , the interface structure  105  includes lateral guide features  138  at its external lateral sides  139  and intermediate guide features  140  at its distal side  137 .  FIG. 17  illustrates how the lateral and intermediate guide features  138 ,  140 , respectively, may be connected to corresponding lateral and intermediate guide rails  138 A,  140 A, respectively, of the receiving station  107 .  FIG. 17  also illustrates how the container support wall  113  and outer lateral walls  151  may receive rough guidance from corresponding walls of the receiving station  107 . 
     As can be seen from  FIG. 13 , the guide features  138 ,  140  may be relatively elongate, for example extending along at least 1, 2, 3 or 4 cm of the second interface dimension d 2 , for example at least 50% or at least 75% or most or all of the length of the second interface dimension d 2 . The guide features  138 ,  140  are to guide the interface structure  105  with respect to the receiving station, to align the fluidic interfaces. For example, the receiving station could include corresponding lateral guide rails  138 A and/or an intermediate guide rail  140 A ( FIG. 17, 20 ). Note that, in other examples, key pens  165  could be used for guidance purposes instead of, or in addition to, at least one of the guide features  138 ,  140 . 
     In the illustrated example, the lateral guide features  138  include first and second lateral guide surfaces  141 ,  141   b ,  145  at angles with respect each other. As will be explained, the first and second lateral guide surfaces  141 ,  141   b ,  145  define a lateral guide slot  142  in the side  139 . The lateral side walls  139   a  may include at least one first lateral guide surface  141 ,  141   b  to facilitate positioning the liquid interface  115  with respect to a liquid needle of the receiving station in a direction parallel to the third interface dimension d 3  and/or at least one second lateral guide surface  145  to facilitate positioning the liquid interface  115  with respect to the needle of the receiving station in a direction parallel to the first interface dimension d 1 . Accordingly, in an example where the supply apparatus  101  is installed approximately horizontally, the at least one first lateral guide surface  141 ,  141   b  may facilitate horizontal positioning of the liquid input  115  and the at least one second lateral guide surface  145  may facilitate vertical positioning. 
     The first lateral guide surfaces  141 ,  141   b  may extend approximately parallel to the first and second interface dimension d 1 , d 2 . The first lateral guide surfaces  141 ,  141   b  may be substantially flat in a plane approximately parallel to said first and second interface dimension d 1 , d 2 , wherein approximately parallel may for example include 10 degrees or less deviation from absolutely parallel. The first lateral guide surfaces  141 ,  141   b  may be elongate along the second interface dimension d 2 , that is, relatively long along the second interface dimension d 2  and relatively short along the first interface dimension d 1 . Where during installation of the supply apparatus  101  the interface structure  105  projects downwards from the bottom  113 , the first lateral guide surfaces  141 ,  141   b  may facilitate approximately horizontal positioning of the liquid interface  115  with respect to a liquid input of the receiving station. 
     A single lateral side wall  139  may have a plurality of first lateral guide surfaces  141 ,  141   b  at a plurality of levels along the third interface dimension d 3 . The lateral guide feature  138  may include two outer first lateral guide surfaces  141  and an inner first lateral guide surface  141   b  that is offset in an inwards direction along the third interface dimension d 3  with respect to the outer first lateral guide surfaces  141 . The inner first lateral guide surface  141   b  may extend between two outer first lateral guide surfaces  141 . The inner and outer first lateral guide surfaces  141 ,  141   b  may span the first interface dimension d 1 , at least approximately. In certain examples only an inner first lateral guide surface  141   b  without the outer first lateral guide surfaces  141 , or only one inner and one outer first lateral guide surface  141 ,  141   b  may be provided, which can be sufficient for positioning the liquid interface  115  along the first and/or third interface dimension d 1 , d 3 . In other examples only one first inner or outer lateral guide surface  141 ,  141   b  may be sufficient to serve the purpose of guiding and positioning, for example together with an intermediate guide feature  140 . In yet other examples, only one of the lateral and intermediate guide features  138 ,  140  is provided. 
     In the illustrated orientation the support wall  137   a  defines the bottom of the interface structure  105 . The support wall  137   a  may include an intermediate guide feature  140 , for example adjacent the liquid interface  115 . The intermediate guide feature  140  may include at least one first intermediate guide surface  143 ,  143   b , to facilitate positioning the liquid interface  115  with respect to the liquid needle while limiting freedom of movement in a direction along the first interface dimension d 1  and/or at least one second intermediate guide surface  147 , to facilitate positioning the liquid interface with respect to the liquid needle while limiting freedom of movement in a direction along the third interface dimension d 3 . The at least one first intermediate guide surface  143 ,  143   b  may extend parallel to the second and third interface dimension d 2 , d 3 . The at least one second intermediate guide surface  147  may extend parallel to the first and second interface dimension d 1 , d 2   
     In one example first intermediate guide surfaces  143 ,  143   b  include an inner intermediate guide surface  143   b , which may extend inwards with respect to the outer surface of the distal side  137 , and two outer intermediate guide surfaces  143  which may define the outer surface of the distal side  137 . Hence, the first intermediate guide surfaces  143 ,  143   b  may extend over multiple levels along the first interface dimension d 1 . The inner first intermediate guide surface  143   b  is adapted to receive and slide over a counterpart guide of the receiving station. The inner first intermediate guide surface  143   b  may be flat along a plane approximately parallel to said second and third interface dimension d 2 , d 3 . The inner first intermediate guide surface  143   b  may be relatively narrow and of elongate shape, that is, relatively long along the second interface dimension d 2  and relatively short along the third interface dimension d 3 . 
     The inner first intermediate guide surface  143   b  may extend between two outer first intermediate guide surfaces  143 . The inner first intermediate guide surface  143   b  may extend adjacent the liquid interface  115  to facilitate positioning of the interface  115  with respect to the needle  109 . The inner and outer first intermediate guide surfaces  143 ,  143   b  may together span a substantial portion of the third interface dimension d 3 , at least approximately. In certain examples only an inner first intermediate guide surface  143   b , without the outer first intermediate guide surfaces  143 , or only one inner and one outer first lateral guide surface  143 ,  143   b  may be provided, which can be sufficient for positioning the liquid interface  115  along the first interface dimension d 1 . 
     Where during installation of the supply apparatus  101  the interface structure  105  projects downwards from the bottom  113 , the first intermediate guide surface  143 ,  143   b  may facilitate vertical positioning of the liquid interface  115  with respect to the liquid input of the receiving station and the first lateral guide surfaces  141 ,  141   b  may facilitate horizontal positioning of the liquid interface  115 . 
     In the illustrated example, the lateral side  139  further includes at least one second lateral guide surface  145  at at least one of the external lateral sides of the interface structure  105 , for example a pair of opposite second lateral guide surfaces  145  at each lateral side, to limit the degree of freedom of the interface structure  105  in a direction along the first interface dimension d 1 . The second lateral guide surfaces  145  can be adjacent to and at an angle with the at least one first lateral guide surface  141 ,  141   b . Said angle can be approximately straight but need not be exactly straight, for example to provide for lead in, manufacturing tolerance or other reasons whereby the angle between the first and second lateral guide surfaces  141 ,  145  could be between approximately 80 and 100 degrees. The at least one second lateral guide surface  145  can be provided between and along the opposite outer first lateral guide surfaces  141  of the same lateral side  139 . The at least one second lateral guide surface  145  can be provided along the inner first lateral guide surface  141   b . The second lateral guide surfaces  145  may extend approximately parallel to the second interface dimension d 2  and third interface dimension d 3  but need not be exactly parallel to achieve said function of limiting the freedom of movement in a direction along the first interface dimension d 1 . 
     For example, the second lateral guide surfaces  145  may be substantially flat, for example along a plane approximately parallel to the second and third interface dimension d 2 , d 3 , wherein approximately parallel may include a 10 degrees deviation from absolutely parallel. The second lateral guide surface  145  may be elongate, that is, relatively long along the second interface dimension d 2  and relatively short along the third interface dimension d 3 . As can be best seen in  FIG. 16 , lead-in ramps  155  can be provided near the front entrance of the second lateral guide surfaces  145 . 
     A pair of opposite second lateral guide surfaces  145  may extend along and on both sides of the inner first lateral guide surface  141   b , for example so that the pair of second lateral guide surfaces  145  and the inner first lateral guide surface  141   b  together form a lateral guide slot  142 . In another example the slot may extend through the side wall  139  without the inner first lateral guide surface  141   b . The outer first lateral guide surfaces  141  may extend at the outsides of the slot  142  parallel to the first interface dimension d 1 . The second lateral guide surfaces  145  and the first lateral guide surfaces  141 ,  141   b  at the opposite lateral sides  139  may facilitate guiding and translating the interface structure  105  in a direction along the second interface dimension d 2  while limiting translations and rotations along and around other axes. The first  141 ,  141   b  and/or second lateral guide surfaces  145  may span a significant portion of the second dimension d 2  of the interface structure  105 , such as at least 50%, at least 75% or most or all of the second dimension d 2 . One or more openings or interruptions can be provided in the guide surfaces  141 ,  145 , such as said lead in ramp  155  or clearances  159 . 
     In other examples, a clearance slot may be provided at the lateral side  139  to clear a corresponding guide rail to facilitate the interfaces structure  105  to be inserted into the receiving station  107  without guidance by the guide rail. In such examples, guidance, if any, may be obtained through walls of the support structure  135  and/or other sides or edges of the interface structure  105  and/or key pens  165 . Such clearance slot may be defined by opposite edges of the lateral side  139 , or between a respective lateral edge and the container side  113  from which the interface structure  105  projects. 
     The intermediate guide feature  140  may be provided with at least one second intermediate guide surface  147  to position the interface structure  105  with respect to the receiving station  107  while limiting a freedom of movement of the interface structure  105  in a direction along the third interface dimension d 3 . The second intermediate guide surface  147  may be at an angle with respect to the first intermediate guide surfaces  143 ,  143   b . For example, such angle could be approximately straight, wherein some margin or tolerance may be included. For example, the angle could be between approximately 80 and 100 degrees. A pair of opposite second intermediate guide surfaces  147  may be provided forming a slot  144 . The second intermediate guide surfaces  147  may be substantially flat, for example along a plane approximately parallel to the first and second interface dimension d 1 , d 2  wherein approximately parallel may include a 10 degrees or less deviation from exactly parallel. The second intermediate guide surface  147  may be of relatively elongate and narrow shape, that is, relatively long along the second interface dimension d 2  and relatively short along the first interface dimension d 1 . 
     The pair of opposite second intermediate guide surfaces  147  may extend at both sides and along the inner first intermediate guide surface  143   b  so that the inner first intermediate guide surface  143   b  and the second intermediate guide surfaces together form an intermediate guide slot  144  in the support wall  137   a  of the interface structure  105 . However, the intermediate guide slot  144  may extend further inwards without the inner first intermediate guide surface  143   b . The outer first intermediate guide surfaces  143  may extend at both sides of the slot  144  parallel to the third interface dimension d 3 . 
     In another example (not illustrated), an intermediate clearance slot is provided at the distal side  137  but the slot is to clear a corresponding guide rail to facilitate the interfaces structure  105  to be fully inserted into the receiving station  107  while avoiding guidance along a corresponding guide rail. For example, as compared to  FIG. 14 , opposite edges of a clearance slot may correspond to second intermediate guide surface  147  whereby the distance between opposite edges of the clearance slot may be greater than the distance between the opposite second intermediate guide surfaces  147 . Guidance, if any, may be obtained through walls of the support structure  135  of other sides or edges of the interface structure  105 . 
     In one example, the intermediate guide feature  140  or the clearance slot is intersected by a virtual reference plane P 0  parallel to the first and second interface dimension d 1 , d 2 , whereby the plane P 0  extends between a center of the liquid interface  115  and a respective key pen  165 , while integrated contact pads  175  extend at another lateral side of the liquid interface  115  opposite to the plane P 0 . 
     As best seen in  FIGS. 14 and 15 , one second intermediate guide surface  147  of the pair of second intermediate guide surfaces  147 , that is closer to the liquid channel  117  and/or interface  115 , may be shorter along the first interface dimension d 1  than the opposite second intermediate guide surface  147  of said pair. The second intermediate guide surface  147  that is closer to the needle receiving liquid channel portion  121  may be narrower to facilitate a thick enough liquid channel wall  117   b  ( FIG. 22 ). Accordingly, in the illustrated example the intermediate guide slot  144  may include a chamfer  148  in its cross section, between the first and second intermediate guide surfaces  143   b ,  147 , respectively, and along at least part of the length of the guide surfaces  143   b ,  147 , adjacent and parallel to the liquid channel  117 , to facilitate space for the channel walls without impeding the guiding and liquid interface positioning function of the intermediate guide feature  140 . Hence, the intermediate guide feature  140  may include approximately perpendicular guide surfaces  143   b ,  147 , including a pair of opposite approximately parallel guide surfaces  147 , perpendicular to an inner guide surface  143   b , wherein said chamfer  148  defines a third guide surface that extends between, and at an angle with, one of the parallel guide surfaces  147  and the inner guide surface  143   b , adjacent to and along the liquid channel  117 . 
     The above-mentioned guide features  138 ,  140  and/or surfaces  141 ,  141   b ,  143 ,  143   b ,  145 ,  147  may be elongate in a direction of the second interface dimension d 2 , and/or flat and flush, to facilitate installation of the interface structure  105  with respect to respective straight counterpart guides of the receiving station. Some of or all the above-mentioned guide surfaces  141 ,  141   b ,  143 ,  143   b ,  145 ,  147  may be provided to facilitate guiding and translating the interface structure  105  along an axis parallel to the needle insertion direction NI while limiting translations and rotations along and around other axes, to align and fluidically connect the liquid interface  115  to the at least one needle  119 . In one example the interface structure may include only one or two of each of the illustrated lateral and intermediate guide features  138 ,  140 , respectively. In one example, at installation, predominantly the second lateral guide surfaces  145  are used for alignment of the interface structure  105  along the first dimension d 1 , D 1  and predominantly the second intermediate guide surfaces  147  are used for alignment along the third dimension d 3 , D 3 , whereby in a sub-example at least one of the other, that is first lateral and first intermediate, guide surfaces  141 ,  141   b ,  143 ,  143   b  need not engage the receiving station guide surfaces or rails  138 A,  140 A at installation or could be omitted from the interface structure design  105 . In a further example the lateral and/or intermediate guide feature  138 ,  140  may include only one or two respective second lateral or intermediate guide surfaces  145 ,  147  without the first lateral or intermediate guide surfaces  141 ,  141   b ,  143 ,  143   b , which in certain instances may be sufficient for guiding and positioning. In again other examples respective guide features  138 ,  140  and/or guide slots  142 ,  144  may include edges which need not be exactly flat and straight surfaces where the edges may be elongate along the second interface dimension d 2 . 
     In an example the first lateral guide surfaces  141 ,  141   b  are approximately parallel to the second intermediate guide surfaces  147 . In an example the first lateral guide surfaces  141 ,  141   b  and/or the second intermediate guide surfaces  147  are approximately parallel to outer lateral walls  151  of the container  3 . In an example the first intermediate guide surfaces  143 ,  143   b  are approximately parallel to the second lateral guide surfaces  145 . In an example the first intermediate guide surfaces  143 ,  143   b  and/or the second lateral guide surfaces  145  are approximately parallel to the side  113  of the container  103  from which the interface structure  105  projects, and/or to an opposite side  132  of the container  103  opposite to the side  113  from which the interface structure  105  projects. Some of these aspects may facilitate a first rough alignment of the container  103  followed by a more precise alignment of the interface structure  105 , as explained earlier. 
     To facilitate proper engagement one or each guide feature  138 ,  140  may be provided with lead-in features. For example, as illustrated in  FIG. 16 , the lateral guide feature  138  includes a lateral lead-in feature  153  near at a front level (in this view indicated by  154 ) of the interface structure  105  to lead in the rest of the guide feature  138  with respect to an external guide rail. In the illustrated example lead-in ramps  155  are provided at the front of both lateral guide slots  142 . The lead-in ramps  155  are defined by opposite diverging lateral guide surfaces, diverging from back towards the front level of the interface structure. The lead-in ramps  155  are a bended or inclined surface with respect to the trailing portion the lateral guide feature  138 . The trailing portion includes the second lateral guide surfaces  145  that may be contiguous with the ramps  155 . The lead-in ramps  155  may be at an angle with respect to the first lateral guide surface  141 ,  141   b , for example at an approximately straight angle, or for example between approximately 80 and 100 degrees with respect to the first lateral guide surface  141 ,  141   b . In an example only one lateral lead-in ramp  155  is provided at one lateral side  139 . 
     A relatively fine alignment may be facilitated by the guide surfaces  141 ,  141   b ,  143 ,  143   b ,  145 ,  147  of the interface structure  105 , for example with the aid of corresponding guide rails and/or surfaces of the receiving station. In a stepped yet relatively fluent fashion, the projecting portion  123  may first engage to the receiving station, providing for relatively rough alignment, then the lead-in features  153  may engage, and then the guide features  138 ,  140  may provide for a finer alignment. For example, the lateral lead-in and guide features  153 ,  138  may provide for first fine alignment while the intermediate guide feature  140  may again allow for a finer alignment. Hence, a proper insertion of the needle with relatively low risk of breaking the needle may be established. The intermediate guide feature  140  extends adjacent to, and along, the liquid interface  115  and channel  117 , to facilitate the relatively precise insertion of the needle. The intermediate guide feature  140  may be connected to the guide rails after the other guide features  138  are connected to provide a final and finest alignment. In certain instances, the liquid volume and associated weight of the supply apparatus  101  can be relatively high which would increase a risk of breaking a fluidic needle, especially in case of relatively uncontrolled push insertion, but this does not need to impede the supply apparatus  101  of some of the examples of this disclosure to readily slide into a relatively precise fluidic connection with the receiving station. In again other examples, some but not all of the disclosed guide features  138 ,  140  are provided and some user control is required for establishing the fluidic connection. 
       FIG. 17A  illustrates a diagram of the guide features  138 ,  140  of the interface structure  105 , in a diagrammatic front view, wherein the guide features  138 ,  140  are adapted to limit the freedom of movement in directions along the third interface dimensions d 3 . For example, the guide features to limit the freedom of movement in a direction along the third interface dimension d 3  include at least one of (i) the inner first lateral guide surfaces  141   b , (ii) the outer first lateral guide surfaces  141   b , and (iii) the second intermediate guide surfaces  147 . In one example each of those surfaces  141 ,  141   b ,  147  may be relatively elongate in the second interface dimension d 2  and may be defined by a ridge or flat surface that engages guide surfaces of the receiving station. A distinction can be made between guide features that limit movement in one direction along the third interface dimension d 3  and guide features that limit movement in the opposite direction along the third dimension d 3 , which is illustrated by continuous lines versus dotted lines in  FIG. 17A . In one example the interface structure  105  includes at least two guide surfaces to limit movement in one direction along the third interface dimension d 3  (e.g.  141 ,  141   b ,  147  in dotted lines) and at least two guide surfaces to limit movement in the opposite direction along the third interface dimension d 3  (e.g.  141 ,  141   b ,  147  in continuous lines). 
       FIG. 17B  illustrates a diagram of the guide features  138 ,  140  of the interface structure  105 , in a diagrammatic front view, wherein the guide features  138 ,  140  are adapted to limit the freedom of movement in directions along the first interface dimensions d 1 . For example, the guide features to limit the freedom of movement in a direction along the first interface dimension d 1  include at least one of (i) the second lateral guide surfaces  145 , (ii) the first inner intermediate guide surfaces  143   b , and (iii) the first outer intermediate guide surfaces  143 . In one example each of those surfaces  145 ,  143   b ,  143  may be relatively elongate in the second interface dimension d 2  and may be defined by a ridge or flat surface that engages guide surfaces of the receiving station. In  FIG. 17B , a distinction can be made between guide features that limit movement in one direction along the first interface dimension d 1  and guide features that limit movement in the opposite direction along the first interface dimension d 1 , which is illustrated by continuous lines versus dotted lines. In one example the interface structure  105  includes at least two guide surfaces to limit movement in one direction (e.g.  145 ,  143 ,  143   b  in continuous lines) and at least two guide surfaces to limit movement in the opposite direction (e.g.  145  in dotted lines). In one example the interface structure may be provided with lateral guide surfaces  145  that are adapted to limit movement of the interface structure  105  in a direction opposite to the projection direction of the interface structure  105 , at least when in contact with corresponding lateral guide rails. 
       FIG. 18  illustrates a cross sectional top view of a system where an example interface structure  105  is connected to a receiving station. The example interface structure  105  includes a secure feature  157 , as also illustrated in  FIGS. 8 and 16 . The secure feature  157  may facilitate operational installation, and in some instances, retention, of the supply apparatus to the receiving station. 
     In these drawings, the secure feature  157  includes a clearance  159 , here in the form of an opening through the lateral wall that defines the lateral side  139 , into which a corresponding secure element of the receiving station  107  may project, wherein the secure element may be a catch or detent, wherein the secure element may be a catch or detent. For example, one secure feature  157  can be provided at one lateral side  139 , or two secure features  157  can be provided at opposite lateral sides  139 . The clearance  159  may be provided near a front side of the interface structure  105 , next to the key pen  165 . In the illustrated example the protruding secure element is a catch hook  161 . However, depending on the application, secure elements other than hooks may be used to facilitate securing the supply apparatus to the receiving station. The secure elements may include blocking features, as is the case for the illustrated hook  161 , audible or tangible feedback features, trigger or switch features, etc. That is, while in one example the secure element may directly lock an interface structure to the receiving station, in other examples the secure element may only trigger a switch or provide for some feedback functionality. 
     In the illustrated example, the secure feature  157  is provided in the lateral guide feature  138 . The clearance  159  may be defined by a cut out in the lateral side  139 , for example in the slot  142  and/or through the inner first lateral guide surface  141   b . In the illustrated example, the clearance  159  is a through hole in the respective side wall, opening into the respective recess  171   a ,  171   b . In other examples, instead of a through hole the clearance  159  could be an indent. Each lateral side  139  may include a secure feature  157 , to interact with secure elements at both sides  139 . The clearance  159  may facilitate that a biased secure element  161  can project partially into the clearance  159   
     The secure feature  157  may further include a stop surface  163 , hereafter also referred to as stop, next to the clearance  159 . The stop  163  can be defined by an edge of the clearance  159  at a side of the clearance  159  that is near the front edge of the interface structure  105 . The stop  163  is provided near a front level of the interface structure as indicated by  154  in  FIG. 16 , for example next to a distal portion of the key pen  165 . The stop  163  may be part of a lateral front wall portion  141   b  that defines the stop as well as an edge of the front of the interface structure  105 , at the entrance of the respective recess. The stop surface  163  may extend at an angle with respect to the adjacent surface of the respective wall portion  141   b  of the lateral side  139 . In one example system, the stop  163  provides for resistance against moving the interface structure  105  with respect to the secure element. In another example system, the stop  163  and/or lateral front wall portion  163   a  may push a finger, trigger or switch or the like to switch into a certain operational mode or to provide certain feedback. 
     As seen in  FIG. 16  a front lateral side wall portion  163   a  may extend between, and define, the stop  163  and the edge around the front. The front lateral side wall portion  163   a  may extend next to a distal portion of the key pen  165 , providing for some protection of the key pen  165  against breaking by falling. The front lateral side wall portion  163   a  may extend between the lead-in ramps  155 . 
     In the illustrated example of  FIG. 18  the secure element is a hook  161 . The hook  161  is shown in a position whereby it projects through the clearance  159 . As will be explained below, this position of the hook  161  can be imposed by a key pen  165  that pushes an actuator of the receiving station that in turn triggers a the hook  161  through a mechanism arranged to transmit the translation to the hook, hereafter referred to as transmission mechanism. In the illustration, some distance is shown between the hook  161  and the stop  163 , which illustrates a moment of installation where the supply apparatus  101  is pushed fully into the receiving station just before the operator manually releases the supply apparatus  101  for completing the insertion. After such release a pushing force of a biased spring will move the stop  163  against the hook  161  in an outward direction out of the receiving station. Thus, the hook  161  counteracts the opposing force F ( FIG. 21 ) of that spring, blocking removal or ejection of the supply apparatus  101  whereby the supply apparatus  101  is retained in fluidic connection. Subsequent retraction of the hook  161  would automatically eject the supply apparatus  101 . 
     A second manual push against the back  125  of the supply apparatus  101  pushes the key pen  165  against the actuator, which may again trigger said transmission mechanism to release the hook  161  with respect to the stop  163  and clearance  159 , whereby the hook  161  is pulled out of the clearance  159 . Thereby, the interface structure  105  is unblocked, which causes the biased spring to expand and push the interface structure  105  out of the receiving station  105 . 
     The stop surface is the stop portion against which a part of the hook  161  is to engage. That engagement surface of the stop  163  may be relatively flat and extend at an angle α with respect to the respective lateral side surface  141   b , for example at an angle α of at least approximately 90 degrees, or slightly more than 90 degrees, for example at an angle α of at least approximately 91 degrees. An angle α of more than 90 degrees may allow for additional retention of the hook  161 , inhibiting slipping of the hook  161  with respect to the stop  163 , or at least inhibit unintended disengagement of the hook  161  to some extent to avoid unintended ejection of the interface structure  105 . 
     Other example supply apparatuses may not have a secure feature. In one example the receiving station may have a hook, grip or arm or the like that retains the supply apparatus  101  against a back of the apparatus. In another example, the supply apparatus  101  is installed to a receiving station in a hung condition (e.g. see  FIG. 43 ) whereby the fluidic connection may be sufficiently secured by the weight of the supply itself, or by manual retention, or by an under-pressure created by a printer pump between the liquid interfaces. In again other examples, the supply apparatus may include a clearance or clearance slot to clear both the guide rail and hook of the receiving station. 
     Other example supply apparatuses may apply other types of secure features than the explained secure feature  157 . These other type secure features may suitably retain a fluidic connection between the supply apparatus and liquid input. For example, the supply apparatus  101  may be provided with a similar secure feature  157  but at a different location, for example at the distal side  137  of the interface structure  105 . For example, the supply apparatus may be provided with a hook, grip or click finger, to hook or unhook to a receiving station, or with high friction surfaces such as elastomeric cushions to press-fit to walls of the receiving station. 
       FIG. 19  illustrates an example interface structure  105  in a perspective view, projecting from a respective side  113  of the container  103 .  FIG. 20  illustrates part of an example receiving station  107  for the example interface structure  105 . A humidor  112  has been omitted in this drawing.  FIG. 21  illustrates a cross-sectional top view of an example where the interface structure  105  and the receiving station  107  are in secured and fluidically connected condition. Amongst others, certain functions and features related to protruding key pens  165  of certain examples of this disclosure will be explained with reference to these  FIGS. 19-21 . 
     The key pens  165  of this disclosure may have a generally longitudinal shape, for example protruding along a longitudinal axis Ck for at least approximately 10, at least approximately 12, at least approximately 15, at least approximately 20 or at least approximately 23 mm. In a first, broader definition of this disclosure a key pen has a “keying” function because it is to pass through a printer key slot to act upon an actuator, for example a switch and/or transmission. In a further example a key pen also has a liquid type (e.g. ink color or agent) discriminating function because it allows for connection to a corresponding receiving station with a matching key slot, while it may be blocked from connection to receiving stations with non-matching key slots. In other examples the key pen may be adapted to have the discriminating function without necessarily having the actuating function. As will be clarified with reference to various example drawings throughout this disclosure, the key pen may have different shapes, ranging from relatively simple protruding pins up to shapes with more complex cross sections. 
     In the illustrated examples, the interface structure  105  comprises a pair of key pens  165 . The key pens  165  extend within the second interface dimension d 2 , as defined by opposite external lateral sides  139 . Correspondingly, the key pens  165  extend within the container dimension D 2 . A pair of key pens  165  may facilitate distribution and/or balancing of forces to actuate respective secure elements as compared to a single key pen. The corresponding actuators that are actuated by the key pens  165  may receive the actuation force in a balanced or distributed manner. Opposite key pens  165  may facilitate better guidance and/or alignment of the interface structure  105  and liquid interface  115 . More than two key pens could be provided, for example with more than one key pen at either side of the liquid channel  117 . The interface structure  105  may also include a pair of secure features  157 , each secure feature at a respective lateral side  139  next to each key pen  165 . In other examples the interface structure  105  comprises only a single key pen  165  or more than two key pens  165 . 
     The key pens  165  may protrude from a base  169 , for example a base wall. The base  169  may be a wall, foot or column. For example, the base  169  may be a wall or foot at a deep end of a respective recess  171   a ,  171   b  within which the key pen  165  protrudes. The base  169  may be offset in a direction backwards, along the needle insertion direction NI, with respect to the interface front  154 . 
     The key pen  165  may extend approximately parallel to the second interface dimension d 2 . The key pen  165  may extend approximately parallel to the respective side  113  the container  103  from which the interface structure  105  projects, for example below a bottom of the container  103 . The container side  113  can be relatively planar and the key pens  165  may extend parallel to that side  113 . In  FIGS. 19-21 , the at least one key pen  165  protrudes along its longitudinal axis Ck that is approximately parallel to the needle insertion direction NI, main liquid flow direction DL, second interface dimension d 2  and/or second container dimension D 2 . The longitudinal axis Ck of the key pen  165  may represent an axis along which the key pen protrudes. The longitudinal axis Ck may be a central axis of the key pen  165 . The key pens  165  extend next to, at opposite sides of, the liquid channel  117  and/or liquid interface  115 , for example generally along a longitudinal direction approximately parallel to a central axis of the needle receiving portion  121  of the liquid channel  117  and/or a central axis of the seal  120 . 
     A distance between a first key pen  165  and the needle receiving liquid channel portion  121 , along the third interface dimensions d 3 , may be greater than a distance between an opposite second key pen  165  and the needle receiving liquid channel portion  121 . The distance could be defined by a distance between an axis representing the needle insertion direction NI and a longitudinal axis Ck along which the key pens  165  extend. The integrated circuit  174  and/or contact pads  175  thereof extend between the first key pen  165  and the needle receiving liquid channel portion  121 . Said greater distance facilitates a data connector  173  to pass between the first key pen  165  and molded structure of the front push area  154   a  and the liquid channel wall  117   b.    
     The key pen  165  is adapted to be inserted in a corresponding key slot  167  of the receiving station  107  ( FIG. 20 ). The key slot  167  may be adapted to facilitate blocking non-corresponding key pens  165  to prevent that non-matching print liquids are connected to the receiving station  107 , for example to prevent contaminating the liquid needle  109  or further liquid channels downstream of that needle  109  with a non-compatible liquid type. In the example of  FIG. 20  the key slot  167  has the shape of a Y in a predetermined orientation, intended to receive only key pens  165  having a correspondingly shaped cross section and corresponding orientation. Other key slots  167  could for example have T-, V-, L-, I-, X- or one or multiple dot shapes or other geometrical shapes. 
     In certain examples, master key pens may be provided that can connect to different key slots  167 , even if the purpose of these key slots is to discriminate between key pens. Master key pens may be provided for service fluid supplies or simply as alternative solutions to color discriminating key pens, and in this disclosure also fall within the definition of a “key pen”. 
     The key pens  165  may be adapted to actuate upon corresponding actuators of associated key slot components. Suitable actuators of a receiving station may include electrical switches and/or mechanical transmission mechanisms. In the example of  FIG. 21 , the actuator is a transmission mechanism including a spring-loaded rod  179 . 
     As illustrated in  FIG. 21 , a distal actuating surface area  168  of the key pen  165  passes through the key slot  167  to actuate upon the rod  179  at insertion of the interface structure  105  into the receiving station  107 . The rod  179  at least partially extends inside a key slot housing component  170  here embodied by a sleeve-shaped housing. At insertion of the supply apparatus  101  into the receiving station  107 , for example by a push of an operator, the housing component  170  is inserted into the recess  171   a ,  171   b , through the recess entrance at the front of the interface structure, towards the base. Thereby the key pen  165  is inserted into the housing component  170  and pushes the rod  179 . In the illustrated example, the corresponding movement of the rod  179  along the main liquid flow direction DL is transmitted to the hook  161  by a suitable transmission mechanism (not shown), whereby an end of the hook  161  is inserted into the clearance  159 . Once the hook  161  is inserted into the clearance and the supply apparatus is released by the operator, the hook  161  may engage the stop  163 , retaining the supply apparatus  101  in the receiving station  107 . The hook  161  may retain the interface structure  105  in seated condition against the spring force F of the rods  179 . In the seated condition, the needle  109  protrudes inside the liquid channel  117  and seal  120 , opening a ball valve  120 A and establishing liquid flow between the supply apparatus  101  and the receiving station  107 . Also, a data connector  173  is connected to the integrated circuit contact pad array  175  whereby data communication may be established. The interface structure  105  may include secure features  157  at both lateral sides  139 , each with clearances  159  and stops  163 . Correspondingly, two opposite hooks  161  may be triggered through the pair of rods  179 . 
     A subsequent push of the operator again moves a rod  179  which again transmits its actuation to the hook  161 . Thereby, the hook  161  is released from the clearance  159  and stop  163 , triggering ejection of the supply apparatus  101 . At ejection, the rod  179  pushes the key pen  165  backwards inside its rod housing component  170  by decompression of the spring, whereby the fluid needle  109  exits the liquid interface  115  and the data connection is broken. 
     In the illustrated example, the interface structure  105  includes two recesses  171   a ,  171   b  both laterally next to the needle receiving portion  121  of the liquid channel  117 , having a depth along the second interface dimension d 2 . The recesses  171   a ,  171   b  may surround the key pens  165 , for example to facilitate intrusion of the key pens  165  into respective key slot housing components  170 . 
     The recess  171   a ,  171   b  may be defined by recess walls. The recess  171   a ,  171   b  may extend next to the needle receiving liquid channel portion  121 , and on the other side the recess  171   a ,  171   b  can be delimited by the inner wall surface of the respective lateral side  139  of the interface structure  105 . The recess  171   a ,  171   b  may further be delimited by, on one side, the side  113  of the container  103  from which the interface structure  105  projects, and, on the opposite side, the inner wall surface of the distal side  137 . 
     The liquid interface  115  and needle receiving channel portion  121  can be laterally offset from a center plane CP of the interface structure  105  (e.g. see also  FIGS. 24 and 25 ), whereby a smaller and larger recess  171   a ,  171   b , respectively, are provided at both sides of the interface  115  and needle receiving channel portion  121 . One key pen may extend at a greater distance from the liquid channel than the other key pen, with an integrated circuit extending between said one key pen and the liquid channel. In one example, the larger recess  171   b  houses the integrated circuit contact pads  175 , that extends on the other side of the center plane CP with respect to the liquid interface  115 . The recess  171   b  may house the entire integrated circuit  174  of which the pads  175  are a part. The integrated circuit  174  can be a microcontroller or other customized integrated circuitry. The integrated circuit contact pads  175  may extend over an inner wall portion of the distal side  137  of the interface structure  105 , in a plane parallel to the second and third interface dimension d 2 , d 3  and along an axis parallel to the third interface dimension d 3 . The distal side  137  includes a support wall portion for the integrated circuit  174 . The integrated circuit contact pads  175  may extend between the liquid channel  117  and the respective key pen  165 . During installation of the supply apparatus  101  a data connector  173  for the integrated circuit contact pads  175  may pass into the respective larger recess  171   b , between the needle receiving channel portion  121  and the respective key pen  165  housed by the respective recess  171   b.    
     The key pen  165  may have an elongate shape in a direction along the second interface dimension d 2 , for example along its longitudinal axis Ck, protruding from the base  169  of the recess  171   a ,  171   b . In one example, the extent of protrusion KL from the base  169  may be based on (i) a desired insertion length of the liquid needle, (ii) an insertion length of the data connector  173 , and (iii) an actuator push length for sufficiently triggering the actuator. In an example, the key pen  165  protrudes inside the respective recess  171   a ,  171   b  along the second interface dimension d 2 , without surpassing the liquid output edge  116  whereby the actuating surface area  168  of the pen  165  may be approximately at level with the liquid output edge  116 . In one example, each protruding key pen  165  is housed in the respective recess  171   a ,  171   b  between the walls  117   b  adjacent to the liquid channel  117 , and walls that define the lateral side  139 . The depth of the recess  171   a ,  171   b , between the interface front  154  and the base  169  along the second interface dimension d 2 , may be approximately the same as the length of the key pen  165 , as measured between that base  169  and a distal actuating surface area  168  of the key pen  165 . In one example some of the walls that extend along the recesses  171   a ,  171   b  may mechanically protect the protruding key pens  165 , for example against damage by falling. 
     The key pen  165  may have a length KL between the base  169  and the actuating surface area  168  of at least approximately 10 mm, at least approximately 12 mm, at least approximately 15 mm, at least approximately 20 mm, or at least approximately 23 mm. Correspondingly, the base  169  of the key pen  165  may extend at least said length KL backwards from the outer edge  116  of the liquid interface  115 , as measured along the second interface dimension d 2 . In the illustrated example the actuating surface area  168  of the key pen  165  extends approximately up to the liquid interface edge  116  but does not extend beyond the liquid interface edge  116 , as measured along the second interface dimension d 2 , or for example up to 1, 2, 3 or 5 mm short of or beyond the edge  116 . In other examples, the distal actuating surface area  168  of the key pen does not protrude further than 3 or further than 5 mm from the outer edge  116  of the liquid interface  115 , as measured along the main liquid flow direction DL or second interface dimension d 2 , while in yet other examples the key pen may extend over more than 5, 10 or 15 mm beyond the liquid interface  115  (e.g. see  FIG. 37A ). 
     In one example the recesses  171   a ,  171   b  are defined by the lateral sides  139 , the support wall  137   a , walls  117   b  that define, or are parallel and adjacent to, the liquid channel  117 , and the respective container side  113  opposite to the support wall  137   a . The lateral side  139  and support wall  137   a  may extend along the key pens  165  for protection, for example at least up to the distal actuating surface areas  168 , or at least up to approximately 5 mm behind the distal actuating surface areas  168 . 
     In the different example supply apparatuses  101 , the container  103  spans along the length KL of the key pen  165 , surpassing the distal actuating surface area  168 , surpassing the liquid interface edge  116  and key pen  165 , and projecting in the main liquid flow direction DL beyond the interface structure  105  over a projection length PP, as illustrated, for example, in  FIG. 8 . 
       FIG. 22  illustrates a cross sectional perspective view of an example of an interface structure  105  and container  103 . For some of the details that will be discussed now with reference to  FIG. 22 , also  FIGS. 5, 6, 8, 9 and 41  may be consulted. In the illustrated example, a reservoir  133 , support structure  135  and interface structure  105  are separately manufactured components that are assembled together after their respective individual fabrication. The example supply apparatus  101  may facilitate using relatively environmentally friendly materials and structures. At the same time, the supply apparatus  101  and receiving station may be implemented in a plurality of different print platforms. The supply apparatus  101  may provide for a relatively user-friendly mounting and unmounting to the receiving station, for example, by a push-push motion. 
     In one example, the support structure  135  is made of carton, or other cellulose based material, for example f-flute cardboard with approximately 2 mm or less, or 1 mm or less thick corrugation. 
     The support structure  135  may be include a generally box-shaped folded carton structure to support and protect the reservoir bag, as well as providing for descriptions, instructions, advertisements, figures, logos, etc. on its outside. The support structure  135  may provide for protection against leakage of the reservoir  133  such as by shocks and/or during transport. The support structure  135  can be generally cuboid, including six generally rectangular sides, defined by carton walls, whereby at least the side  113  from which the interface structure  105  projects may include an opening  113 A to allow liquid to flow from the reservoir  133  through the support structure  135  and the interface structure  105 . The opening  113 A can be provided adjacent a second side  125  that is at approximately right angles with the first mentioned side  113 . In some of the illustrated examples the opening  113 A is provided in the bottom wall near the back wall to allow for the interface structure to project from the container bottom near the back whereby the container volume may project beyond the liquid interface in the main direction of outflow of the liquid, along the main liquid flow direction DL. The support structure  135  may include a push indication on or along said second side  125 , e.g. the back side, to indicate to an operator to push against that side  125  for mounting and/or unmounting the supply apparatus  101 , respectively. 
     In one example, the reservoir  133  includes a bag of flexible film walls, the walls comprising plastic film that inhibits transfer of fluids such as gas, vapor and/or liquids. In one example, a laminate of multi-layered thin film plastics may be used. Thin film material may reduce the use of plastic material, and consequently, the potential environmental impact. In a further example a thin metal film may be included in the multiple layers to increase impermeability. The flexible film reservoir walls may include at least one of PE, PET, EVOH, Nylon, Mylar or other materials. 
     In different examples, the reservoirs  133  of this disclosure may facilitate holding at least 50 ml, 90 ml, 100 ml, 200 ml, 250 ml, 400 ml, 500 ml, 700 ml, 1 L, 2 L, 3 L, 5 L or more print liquid. Between different volume containers  103 , the same reservoirs  133 , having the same maximum liquid volume capacity, can be used for different support structures  135  and/or different liquid volumes of the supply apparatus  101 . 
     The reservoir  133  may include a relatively rigid interconnect element  134  more rigid than the rest of the flexible bag, for fluidic connection to the interface structure  105 , allowing the liquid in the reservoir  133  to flow to the receiving station. In the illustrated example of  FIG. 22  the interconnect element  134  may be a neck of the reservoir including a central output channel through which liquid is to flow out of the reservoir  133 , the neck including flanges extending outwards from the central output channel to facilitate attachment to the respective support structure wall at the edge of the opening  113 A, as well as a central channel to channel the liquid to the liquid channel  117 . The interconnect element  134  may connect to the reservoir connecting portion  129  of the liquid channel of the interface structure  105 , for example to a protruding portion of the reservoir connecting portion  129  that extends beyond the first interface dimensions d 1  into the support structure  135 , that is, beyond the profile height of the interface structure  105 . 
     The interconnect element  134  may facilitate interconnection of the reservoir  133 , support structure  135  and reservoir connecting liquid channel portion  129 . The different flanges may connect to different components. For example, a first flange of the interconnect element  134  may connect to the reservoir  133  and a second flange may connect to the support structure  135 . In one example the reservoir comprises film laminate where by one film layer is attached over one side of the flange and another film layer is attached over the other side of the flange in a fluid tight manner. The film layers may be welded to the flange. A mechanical connection structure  106  may be provided to clamp the reservoir  133  and support structure  135  to the reservoir connecting liquid channel portion  129 , for example between flanges of the interconnect element  134  and wedged arms of the mechanical connection structure  106 , whereby the arms of the mechanical connection structure  106  may extend around the tubular reservoir connecting liquid channel portion  129  and clamp the reservoir and support structure walls between flanges of the interconnect element  134  and its wedges. 
     The reservoir bag may project inside the projecting portion  123  of the support structure  135  beyond the liquid interface edge  116 , for example, as can be seen with reference to  FIG. 41 . For example, more than 60, 70, 80, or 90% of a length of the reservoir along the second container dimension D 2  projects away from the interconnect element  134 , in an operational and at least partially filled condition of the reservoir  133 . To that end, the interconnect element  134  may be provided in the reservoir at an asymmetrical position, for example near an edge or corner of an unfilled and flat reservoir bag. 
     The interface structure  105  comprises relatively rigid molded plastics. The walls of the interface structure may inhibit transfer of fluids such as gas, vapor and/or liquid, so that the separate reservoir and interface structure may together form a relatively fluid tight liquid supply system. Most of the interface structure  105 , such as the base  169 , back  126  and side walls  139 ,  137 , may be made of recycled fiber filled plastics material, such as a non-glass fiber recycled PET. In one example the non-glass fill provides for better retention of the seal  120  in the liquid channel  117 . For example, the key pens  165  and an example separate mechanical connection structure  106  ( FIG. 40 ) may be made of glass fiber filled plastics. 
     While the materials of the interface structure and reservoir may be relatively impermeable to fluids, in practice, some fluids may be transferred through walls of the reservoir and interface structure over time for various reasons. Correspondingly, a certain limited shelf life may be associated with the supply apparatus  101 . For example, a choice of materials may be based on reducing the reservoir film thickness while maintaining a certain minimum shelf life. In one example, an interconnect element  134  separate from the reservoir  133 , in use assembled between the interface structure  105  and the reservoir  133 , may be more fluid permeable than the interface structure  105  and reservoir  133  to facilitate attachment of the interconnect element  134  to the interface structure  105  and reservoir  133  that are of different materials, for example to facilitate both welding and gluing. 
     The liquid throughput  111  of the interface structure  105  and its main liquid flow path LFP are illustrated in  FIG. 22 . The main direction of flow of the liquid flow path LFP is out of the container and interface structure  205  as explained earlier but in certain examples there may be a bi-directional flow path associated with the liquid flow path LFP, or opposite flow where there are two liquid channels  117 . Upstream of the main direction of flow along the main liquid flow path LFP, the interface structure  105  may be provided with a liquid channel input  124 , for example aligned with the interconnect element  134  of the reservoir  133 , to receive liquid from the reservoir  133 , as part of the liquid receiving liquid channel portion  129 . Downstream of that input  124  the liquid channel of the supply apparatus  101  includes the rest of the reservoir connecting channel portion  129 , followed by the intermediate channel portion  119 , the needle receiving channel portion  121 , and the liquid interface  115 . In the illustrated example, the intermediate liquid channel portion  119  facilitates (i) an angle β between the reservoir connector portion  129  and the needle receiving portion  121  in a plane parallel to the first and second interface dimension d 1 , d 2  and (ii) and a lateral offset between the reservoir connector portion  129  and the needle receiving portion  121  along the third interface dimension d 3 . 
     The needle receiving channel portion  121  is adapted to receive a straight fluid needle  109  of a receiving station when inserted through the liquid interface  115 . The needle receiving portion  121  is at angles with the reservoir connecting portion  129  to allow liquid to first flow from the reservoir  133  to the interface structure  105  and then along a curve towards the liquid input  124  of the liquid channel  117 . The angle β between central axes of the reservoir connecting channel portion  129  and the needle receiving channel portion  121  may be approximately straight, as seen in a direction along the third interface dimension d 3 , as diagrammatically illustrated in  FIG. 23 . For example, in an approximately horizontally installed supply apparatus with a downwards protruding interface structure  105  the reservoir connecting portion  129  may have an approximately vertical central axis and the needle receiving portion  121  may have an approximately horizontal central axis. In other examples the angle β may be different, for example between 45 and 135 degrees, as shown by the dotted lines  129   a ,  129   b  that illustrate potentially differently inclined central axes of the reservoir connecting portion  129   a ,  129   b  with respect to the needle receiving liquid channel portion  121 . The reservoir connecting liquid channel portion  129  may project from the interface structure  105  to connect to the reservoir  133 . 
     In a further example, the needle receiving portion  121  is laterally offset from the reservoir connecting portion  129  along the direction of the third interface dimension d 3 , as can be seen in  FIGS. 22 and 24 . For example central axes of the needle receiving channel portion  121  and the reservoir connecting channel portion  129  may extend in different reference planes C 121 , CP, respectively, each of these planes C 121 , CP being (i) parallel to the first and second interface dimensions d 1 , d 2 , and (ii) offset with respect to each other. The lateral offset distance of the channel portions  121 ,  129 , e.g. as measured between the planes C 121 , CP, can be approximately the sum of the channel radii of the reservoir connecting channel portion  129  and the needle receiving channel portion  121 . In the illustrated example a central axis of the reservoir connecting channel portion  129  extends approximately in the center plane CP of the interface structure  105 , wherein the needle receiving channel portion  121  is offset and parallel with respect to the center plane CP of the interface structure  105 . 
     Off centering the needle receiving channel portion  121  with respect to the center plane CP may facilitate a larger recess  171   b  next to the needle receiving channel portion  117  which in turn facilitates housing the integrated circuit and contact pads  175  and respective key pen  165 , and the corresponding insertion of the data connector  173  and the key slot housing component  170 . The integrated circuit contact pads  175  and the liquid interface  115  may be disposed on laterally different sides of the center plane CP. 
     The explained aspects of the dimensions, positions and orientations of the different interface components in the interface structure  105  may facilitate relatively small-width and low-height profile interface structure  105 , e.g. with relatively small first and third interface dimensions d 1 , d 3 , which in turn may facilitate compatibility with a relatively wide range of different container liquid volumes and different print systems. For example a first dimension d 1  versus third dimension d 3  (e.g. height versus width) aspect ratio of the projecting portion of the interface structure  105  can be less than 2:3, or less than 3:5, or less than 2:5, or less than 3:10, for example approximately 1.3:4.8, respectively. For example, a first dimension d 1 :second dimension d 2  (e.g. height:length) aspect ratio of the projecting portion of the interface structure  105  can be less than 2:3, or less than 3:5, or less than 2:5, or less than 3:10, for example approximately 1.3:4.3, respectively. In one example said first dimension d 1  is between approximately 10 and 15 mm. A relatively small first dimension d 1  of the projecting portion of the interface structure  105  may facilitate connecting an interface structure  105  to mount to both relatively large volume containers  103  such as more than 500 ml as well as to relatively small volumes such as for example approximately 100 ml or less. Reservoir volumes may include at least 50 ml, 90 ml, 100 ml, 200 ml, 250 ml, 400 ml, 500 ml, 700 ml, 1 L, 2 L, 3 L, 5 L, etc. 
     Also, the small interface dimension d 1  may facilitate relatively efficient stacking and transport of the supply apparatuses  101 . In certain examples the ratio of the first dimensions D 1 :d 1  of the container  103  versus the projecting portion of the interface structure  105  could be more than 5:1, more than 6:1 or more than 7:1. 
       FIGS. 24 and 25  illustrate examples of interface structures  105  in a cross sectional top view and in a front view, respectively.  FIG. 24  illustrates virtual reference planes P 1 , P 2 , P 3 , P 4 , each plane P 1 , P 2 , P 3 , P 4  parallel to the first and third interface dimension d 1 , d 3 , and offset with respect to each other along the second dimension d 2  from a front  154  to a back  126  or the interface structure  105 . One or more of these virtual planes P 1 , P 2 , P 3 , P 4  can be used to describe the relative position and shape of the different interface components of the interface structure  105 . 
     In the illustrated example of  FIG. 24 , the first plane P 1  tangentially touches or intersects at least one of the interface front  154  and the key pen  165 . In one example, the interface front  154  comprises an approximately straight surface whereby the surface extends approximately parallel to the first plane P 1  and the first plane P 1  touches the interface front  154 . In a further example the first plane P 1  intersects or touches the key pen  165  near or through its distal actuating surface area  168 . In another example the key pen may include an extended pen portion that protrudes beyond the interface front  154  whereby the first plane P 1  intersects the extended pen portion. In yet another example the key pen stops short of the interface front  154  whereby the first plane P 1  does not touch or intersect the key pen. In the illustrated example, the first plane P 1  does not touch or intersect the integrated circuit contact pads  175  but in another example the contact pads  175  could be moved somewhat and the first plane P 1  could touch or intersect the contact pads  175 . 
     The second plane P 2  is provided parallel to the first plane P 1 , and away from the front  154  along the needle insertion direction NI. For example, the second plane P 2  is provided at a distance from the interface front  154  and/or the key pen actuating surface areas  168 . The second plane P 2  intersects, along the third interface dimension d 3 , from left to right in the figure, at least, one of the lateral side walls  139 , the support wall  137   a , one of the recesses  171   b , one of the key pens  165 , the array of integrated circuit contact pads  175 , the needle receiving liquid channel portion  121  (for example including the seal  120 ), another one of the recesses  171   a , another one of the key pens  165  and another one of the lateral side walls  139 . In an example the lateral side walls  139  include lateral guide features  138  and the second plane P 2  intersects these lateral guide features  138 . In another example, the support wall  137   a  includes the intermediate guide feature  140  (not visible in  FIG. 24 ) and the second plane P 2  intersects the intermediate guide feature  140 . The intermediate guide feature  140  may be provided under the first recess  171   a  and next to the liquid throughput  117  opposite to the second recess  171   b . Most or all of said interface features may be integrally molded portions of a single molded, monolithic interface structure  105 , while for example the key pens  165  and seal  120  may form separate plug-in components, although the pens  165  could be integrally molded with the rest. The integrated contact pads  175  may form part of separate elements of an integrated circuit that stores and controls certain print related functions, that is separately adhered to an inner surface of the support wall  137   a  of the interface structure  105 , in the second recess  171   b . In use, the contact pad contact surfaces face the container  103 , and the contact pads  175  are disposed in the respective recess  171   b  on the inside of the support wall  137   a , between the liquid channel  117  and one of the key pens  165 . The integrated circuit  174  may be separately assembled to the integrally molded, monolithic structure, for example by adhering a carrier board of the circuit to the support wall  137   a.    
     The third plane P 3  is provided parallel to the second plane P 2 , offset from the second plane along the needle insertion direction NI, further distanced from the interface front  154  than the second plane P 2 , and intersects, along the third interface dimension d 3 , from left to right in the figure, at least, a clearance  159 , one of the recesses  171   b , one of the key pens  165 , the liquid channel  117  (for example the needle receiving channel portion  121 ), another one of the recesses  171   a , another one of the key pens  165  and another clearance  159 . The third plane P 3  may intersect portions of the lateral side walls  139  and the support wall  137   a . For example, the third plane P 3  is provided at a distance from the integrated circuit contact pads  175 . The third plane P 3  may also be provided at a distance from the seal  120 . In an example the lateral side walls  139  include lateral guide surfaces  141 ,  145  and the third plane P 3  intersects these lateral guide surfaces  141 ,  145 , wherein the lateral guide surface may include first and second lateral guide surfaces  141 ,  145  as explained elsewhere in this disclosure. In another example, the support wall  137  includes the intermediate guide feature  140  (not visible in  FIG. 24 ) and the third plane P 3  intersects the intermediate guide feature  140 . The intermediate guide feature  140  may be provided next to the liquid throughput  117  and under the first recess  171   a . In other examples only one or none of the two clearances  159  are provided. 
     As illustrated in  FIG. 24 , a center plane CP may intersect the interface structure  105  through a middle of the third interface dimension d 3  and may extend parallel to the first and second interface dimensions d 1 , d 2 . The center plane CP may also intersect the container  103  through a middle of the third container dimension D 3 . The center plane CP may intersect the interface front  154  and the liquid interface  115 . The integrated circuit contact pads  175  may be provided on one side of the center plane CP, and the needle receiving liquid channel portion  117  and liquid interface  115  are provided on the other side of the center plane CP. Key pens  165  may be provided on opposite sides of the center plane CP. The second recess  171   b , that houses the integrated circuit contact pads  175 , is larger than the first recess  171   a . The center plane CP may intersect part of the second recess  171   b  so that most of the second recess  171   b  extends on the opposite side of the center plane CP with respect to the first recess  171   a.    
     The fourth virtual plane P 4  is provided parallel to the third plane P 3  further removed from the front  154  along the needle insertion direction NI. The fourth plane P 4  intersects, along the third interface dimension d 3 , the lateral side walls  139 , the support wall  137   a , and the reservoir connecting portion  129  of the liquid channel  117 . In a further example, the fourth plane P 4  also intersects an intermediate portion  119  of the liquid channel  117 . The reservoir connecting portion  129  of the liquid channel  117  may include an at least partly cylindrical wall (e.g. see  FIG. 26 ) around a second central axis parallel to the first interface dimension d 1 , the central axis indicated in  FIG. 24  by the intersection of the center plane CP and the fourth plane P 4 . The fourth plane P 4  may extend along the base walls  169 , for example near the base walls  169  at approximately 0 to 5 or 0 to 3 mm from the base walls  169 . The fourth plane P 4  may be provided at a distance from the contact pads  175 , seal  120  and clearance  159 . 
       FIG. 24  also illustrates the generally rectangular contour of the interface structure  105 , along its second and third interface dimension d 2 , d 3 . The generally rectangular contour may be defined by a front edge of the distal side  137 , a back  126 , and two opposite lateral sides  139 . The front edge of the distal side  137  and/or a back  126  may include an approximately straight outer edge or surface approximately parallel to the third interface dimension d 3 . The lateral sides  139  may include approximately straight edges or surfaces approximately parallel to the second interface dimension d 2 , such as first lateral guide surfaces  141 . The extents of the rectangular contour may be approximately 5 cm or less along the third interface dimension d 3  and/or approximately 6 cm or less along the second interface dimension d 2 , for example 48 and 43 mm, respectively. 
       FIG. 25  illustrates the example interface structure  105  of  FIG. 24  intersected by virtual reference planes P 5 , P 6 , P 7 , P 8 , P 9  each parallel to the second and third interface dimension d 2 , d 3 , and offset with respect to each other along the first dimension d 1 , in a projection direction of the interface structure  105 , that is, each plane closer to the distal side  137  of the interface structure  105 . In the direction towards the distal side  137 , the planes include, respectively, a fifth plane P 5 , a sixth plane P 6 , a seventh plane P 7 , an eighth plane P 8 , and a ninth plane P 9 , respectively. 
     The fifth plane P 5  intersects the edge  154   b  of the interface front  154 , and for example a protruding reservoir connecting portion  129  of the liquid channel  117 . For example, the fifth plane P 5  may further intersect at least one of the lateral side walls  139 , the recesses  171   a ,  171   b , and the bases  169  of the recesses  171   a ,  171   b  and keys  165 . The fifth plane P 5  may intersect a first lateral guide surface  141 ,  141   b , for example an outer first lateral guide surface  141 . The fifth plane P 5  may extend at a distance from the key pens  165 , for example at least at a distance from the actuating surface area  168  of the key pens  165  and/or at a distance from the edge  116  of the liquid interface  115 . 
     The sixth plane P 6  intersects the lateral side wall  139 , one of the recesses  171   a , the key pen base  169 , one of the key pens  165 , the needle receiving liquid channel portion  121  at a distance from the central axis of the liquid interface  115  and/or needle receiving portion  121 , the seal  120  above its central axis, the second recess  171   b , another key pen base  169 , the other key pen  165  and the other lateral side wall  139 . Said central axes may extend in the middle of the seal  120  straight into the drawing. In the illustrated example, the sixth plane P 6  intersects the key pens  165  through their central axes Ak that extend at a straight angle with the base  169  of the key pen  165 , through the middle of the key pen  165 , along the length of the key pen  165 . The sixth plane P 6  may intersect a first lateral guide surface  141 ,  141   b , for example an inner first lateral guide surface  141   b , and/or the clearance  159  and/or the stop  163 . 
     The seventh plane P 7 , at a distance from the sixth plane P 6 , intersects the lateral side wall  139 , one of the recesses  171   a , the key pen base  169 , one of the key pens  165 , a central axis of the liquid interface  115  and the needle receiving portion  121  of the liquid channel  117 , the second recess  171   b , another key pen base  169 , another key pen  165  and the other lateral side wall  139 . The seventh plane P 7  may intersect the first lateral guide surface  141 ,  141   b , for example the inner first lateral guide surface  141   b , and/or the clearance  159  and/or the hook stop  163 . The seventh plane P 7  may extend at a distance from the central axes of the key pens  165 . The fifth, sixth and seventh plane P 5 , P 6 , P 7  extend at a distance from the integrated circuit contact pads  175 . 
     In other examples, the key pens  165  could be moved downwards in the drawing of  FIG. 25 , as compared to how he key pens  165  are currently positioned in the drawing, so that the central axes Ak of the key pens  165  would be intersected by (i) the same plane, or (ii) a plane at the other side of, the plane that intersects the central axes of the liquid interface and needle receiving channel portion. In the first example the central axes of the key pens and liquid interface would be at the same level along the first interface dimension d 1 . 
     The eighth plane P 8 , at a distance from the seventh plane P 7 , intersects the integrated circuit contact pad array  175  and/or rest of the integrated circuit  174 . The eight plane P 8  may extend adjacent, and/or just touching, the support wall  137   a  that defines the external distal side  137  of the interface structure  105 . The support wall  137   a  supports the integrated circuit  174 . The integrated circuit contact pads  175  may have contact surfaces extending, at least approximately, in and/or parallel to said eighth plane P 8 . The contact surfaces may be planar whereby the planes of the contact surface may approximately extend in said eight plane P 8 , although it will be understood that these surfaces are in practice not exactly planar so that some deviation of portions of the contact surfaces from the eight plane P 8  may be taken into account. In one example the integrated circuit contact pads  175  are part of a circuit that is provided in a relatively shallow cutout in the inner support wall  137   a , whereby the eighth plane P 8  may also intersect or touch the support wall  137  at lateral sides of the contact pads  175 . The eighth plane P 8  may extend at a distance from the key pens  165 . Depending on the size and shape of the liquid interface edge  116 , the eighth plane P 8  may approximately tangentially touch or intersect the liquid interface edge  116 , or may be slightly distanced from that edge  116 . The eighth plane P 8  intersects the lateral sides  138 . The eighth plane P 8  may intersect a wall or rib  144   b  extending along, and partly defining, the intermediate guide slot  144 , the wall or rib  144   b  protruding into the respective recess  171   a.    
     The ninth plane P 9  extends at a small distance from the eighth plane P 8 , and intersects the support wall  137   a  at a distance from the contact pads  175 , whereby the wall  137   a  supports the integrated circuit contact pads  175  and/or the integrated circuit  174  and defines the distal side  137 . The ninth plane P 9  may intersect the intermediate guide feature  140 , here embodied by the guide slot  144 . The ninth plane P 9  extends at a distance from the key pens  165 , the liquid interface edge  116 , and the needle receiving liquid channel portion  121 . The ninth plane P 9  extends adjacent the external surface of the distal side  137  of the interface structure  105 . 
     As illustrated, the interface structure  105  can be defined by a series of virtual planes P 5 -P 9  that are parallel to the second and third dimension d 2 , d 3  of the interface structure  105 , including (i) an intermediate plane P 6  or P 7  that intersects the liquid interface  115 , and the recesses  171   a ,  171   b  and respective key pens  165  at both sides of the liquid interface  115 , (ii) a first offset plane P 8 , P 9 , parallel to and offset from the intermediate plane P 6  in the projection direction of the interface structure  105 , the first offset plane P 8 , P 9  intersecting a support wall  137   a  that supports the integrated circuit and/or an integrated circuit contact pad array  175 , said contact pad array extending along a line parallel to that plane P 8 , P 9  and the third interface dimension d 3 , and (iii) a second offset plane P 5  parallel to and offset from the intermediate plane P 6  or P 7  in a direction opposite to the projection direction of the interface structure  105 , the second offset plane P 5  intersecting the interface front edge  154   b  of the interface structure  105  at a distance from the liquid interface  115 , and intersecting a reservoir connecting liquid channel portion  129  that connects to the liquid supply container  103 . The first offset plane P 8 , P 9  and second offset plane P 5  extend (i) at opposite sides of the intermediate plane P 6  or P 7 , (ii) at a distance from the key pens  165 , and (iii) at a distance from inner walls of the needle receiving channel portion  121 . The inner walls of the needle receiving channel portion  121  extend between the offset planes P 5 , P 9 . In the illustrated example the offset planes P 5 , P 9  also extend at a distance from the liquid interface edge  116 , which in one example is defined by edges for the interface front  154  in which the seal  120  is inserted. When the interface structure  105  is attached to the container  103 , these planes P 5 , P 6  or P 7 , P 8  may extend parallel to the container side  113  from which the interface structure  105  projects. As explained, the interface structure  105  may be of relatively low profile, whereby the distance between the opposite offset planes P 5 , P 9  may be between less than approximately 20 mm, less than approximately 15 mm, less than approximately 13 mm, or less than approximately 12 mm, approximately corresponding to the extent of the first interface dimension d 1  which may correspond the height of the projecting portion of the interface structure  105 . In further examples the intermediate plane P 6  or P 7  intersects the clearance  159  and/or the stop  163  and/or the lateral guide features  138 . The offset planes P 5 , P 9  may be provided at a distance from the clearance  159 . 
       FIG. 26  illustrates a separate interface structure  105 . The interface structure  105  comprises a single relatively rigid molded plastic base structure  105 - 1 , whereby for example the key pens  165  and seal  120  may be separate components, for example plugged into corresponding complementary holes and a channel, respectively. Further separate components may be assembled to the single relatively rigid molded plastic structure, such as a channel connector component  181  to connect to the reservoir  133 . 
     As can be seen the lateral sides  139  project from the support wall  137   a  in a direction of the first dimension d 1 . The external side of the support wall  137   a  is referred to as distal side  137  elsewhere in this disclosure. The explained projecting components project from the internal side opposite to the external side  137 . The support wall  137   a  and its external side  137  generally extend parallel to the second and third interface dimensions d 2 , d 3 . The liquid channel  117  may be part of a protruding structure protruding from the support wall  137   a  in the direction of the first interface dimension d 1  along the second interface dimensions d 2 , the structure including the tubular liquid channel wall  117   b  and a block that defines the front push area  154   a  and liquid interface  115 . Said structure of the liquid channel  117  extends between the recesses  171 ,  171   b . The bases  169   a ,  169   b  of the recesses  171   a ,  171   b  and/or key pens  165  may also project from the wall  137   a  in the direction of the first interface dimension d 1 . Each recess  171   a ,  171   b  extends between said liquid channel structure, a lateral side wall  139  and the base  169   a ,  169   b . Further walls, such as a back wall  154   d  may also project from the support wall  137   a  in the direction of the first interface dimension d 1 . 
     The reservoir connecting channel portion  129  includes a channel connector component  181  to connect or seal to the reservoir  133 . The reservoir connecting channel portion  129  protrudes in a direction parallel to the first dimension d 1 , for example at a straight angle with the main liquid flow direction DL or needle insertion direction NI, to connect to a liquid reservoir  133 . The reservoir connecting channel portion  129  may include a cylindrical liquid channel extending partly inside and partly outside of the first interface dimension d 1 , with the connector component  181  at its upstream end, for example to further facilitate connecting to the reservoir  133  inside the support structure  135 . As illustrated, the protruding reservoir connecting channel portion  129  protrudes outside of the extent of the first interface dimension d 1 , by a certain extent OUT, to pass through an opening  113 A ( FIG. 22 ) in a respective support structure side  113 . 
     In other examples (not illustrated) the reservoir connecting liquid channel portion  129  may not protrude beyond the height of the interface structure  105 , fully extending inside the first interface dimension d 1 , whereby for example the reservoir-side interconnect element  134  may extend through the support structure opening  113 A at least partly into or up to the interface structure  105  to fluidically connect to the liquid channel  117 . 
     The connector component  181  and/or the liquid interconnect element  134  may include a ring, neck, screw-thread or the like, as illustrated in both  FIGS. 22 and 26 . The connector component  181  and/or the liquid interconnect element  134  may connect to the reservoir connecting liquid channel portion  129  and a neck of the reservoir  133 , respectively. The internal diameters of the connector component  181 , liquid interconnect element  134  and reservoir neck may correspond. An internal diameter of the liquid interconnect element  134  and/or reservoir neck is smaller than total width of the reservoir  133  along the third container dimension D 3 . For example, the internal diameter may be less than half the width of the reservoir  133 . In some examples (such as  FIGS. 46, 47 ), the neck of the reservoir  133  may be relatively small as compared to the dimensions of the reservoir  133 . 
     The first interface dimension d 1  may be defined by a distance between an outer edge of the distal side  137  and the front edge  154   b . Also, opposite edges of the lateral side  139  may approximately define the first interface dimension d 1 . 
     As illustrated in  FIG. 26 , the single molded structure may be open opposite to the support wall  137 . For example, the recesses  171   a ,  171   b  of the interface structure  105  are open opposite to the support wall  137   a , whereby in assembled condition the respective container side  113  closes that opening to form a recess wall opposite to the support wall  137   a.    
     The lateral walls  139  and support wall  137   a  terminate at edges at the front  154  of the interface structure  105 . The edges extending at the entrance of the recesses  171   a ,  171   b , whereby a proximal and distal front edge  154   b ,  154   c  may is provided adjacent the liquid interface  115 . 
     The recesses  171   a ,  171   b  are each provided with a base  169   a ,  169   b , which may also be the base  169   a  of the respective key pen  165 . The base  169   a ,  169   b  forms an inner wall of the recess  171   a ,  171   b , extending between a liquid channel wall  117   b  and the lateral side walls  139 . The base  169   a ,  169   b  may extend parallel to the third interface dimension d 3 . The base  169   a ,  169   b  may be defined by a wall parallel to the first and third interface dimensions d 1 , d 3 . The base  169   a ,  169   b  is offset in a direction backwards (opposite to the main flow direction DL) with respect to the interface front  154 , wherein the offset distance may be approximately the same as the length of the key pens  165 . In other examples the base  169   a ,  169   b  may be offset further backwards than as shown in the drawing and the key pen length may be correspondingly extended such that the actuating end area  168  of the pen is approximately aligned with the liquid interface edge  116 . In a further example the base  169   a ,  169   b  may be an inner wall that is offset from a back wall  154   d  of the interface structure  105  in a direction inwards along the second interface dimension d 2 . Space  154   d  may be provided between the back wall  154   d  and the base  169   a ,  169   b , for example for click fingers of the key pen  165 . 
       FIG. 27  illustrates an example of a key pen  165 , attachable to a base wall  169   a  of a corresponding interface structure  105 . The key pen  165  includes a protruding longitudinal key pen portion  165   b  of at least approximately 10 mm, at least approximately 12 mm, at least approximately 15 mm, at least approximately 20 mm, or approximately 23 mm, extending from the key pen base  169   b  up to the key pen actuating surface area  168 . In use, the protruding longitudinal key pen portion  165   b  may protrude from the key pen base  169   b , along a pen axis Ck of the key pen  165 , the pen axis Ck extending in an insertion direction which may be parallel to the main liquid flow direction DL. In the illustrated example, the pen axis Ck extends at a straight angle with the key pen base  169   b  and parallel to the second interface dimensions d 2 . The key pen base  169   b  may form part of the base  169   a ,  169   b  of the recess  171   a ,  171   b  when the key pen  165  installed in the interface structure  105 . 
     In this disclosure, when referring to a “base” of the key pen, a base of the key pen may refer to any base wall portion adjacent the key pen and from which the key pen protrudes, at least a condition where the key pen is assembled to its respective base wall. Such base could in one example be an integrally molded portion  169   b  of the key pen, or in another example a portion that is separately molded from the key pen. In disassembled condition of the key pen the base may refer to a base portion  183  of the disassembled key pen from which the rest of the key pen protrudes towards its actuating surface area  168 , for example such as illustrated in  FIG. 27 . In examples where the key pen is integrally molded with a base wall  169  of the recess  171   a ,  171   b , or where the key pen is pre-assembled to such base wall  169 , any base wall portion  169 ,  169   a ,  169   b  adjacent the key pen from which the key pen protrudes may define the base of the key pen. 
     At installation (e.g. see  FIG. 21 ), the protruding longitudinal key pen portion  165   b  may at least partially protrude inside the key slot housing component  170  over a pen insertion distance of at least 10 mm, 12 mm, 15 mm, or 20 mm. The pen insertion length should be sufficient to activate the actuator. For example, the pen insertion length includes a first distance to engage a transmission mechanism (e.g. rod  179 ), for example 1.5 mm, and a second distance to further push the transmission mechanism for actuation, for example, actuating upon a switch or hook  161 . The second distance could be at least 8.5 mm, at least 10.5 mm, at least 13.5 mm, at least 18.5 mm, etc. The total length of the key pen  165  between the base  169 ,  169   a ,  169   b  and the distal actuating surface area  168  should span at least that pen insertion distance. 
       FIG. 28  illustrates an example of a key pen  165  inserted in an interface structure  105 . As can be seen the key pen base  169   b  is defined by a base portion  183  that in use is inserted in the interface structure  105 , co-defining the base  169   a ,  169   b  of the longitudinal key pen portion  165   b . The base portion  183  may be substantially cylindrical or differently shaped, extending along the longitudinal axis Ck, backwards from the key pen base  169   b . The pen axis Ck may extend through the center of the cylindrical base portion  183 . 
     In an example, the base portion  183  and the longitudinal key pen portion  165   b  form an integrally molded single piece. The base portion  183  is inserted in a corresponding pen base hole  185  of the interface structure  105 . The pen base hole  185  is provided in the base wall  169   a  of the respective recess  171 . The base wall  169   a  extends next to the liquid throughput  111 , offset with respect to the liquid interface  115  along the needle insertion direction. In the illustrated example the key pen base  169   b  is approximately leveled with the surface of the surrounding base wall  169   a , the key pen base  169   b  and base wall  169   a  together forming the base of the respective recess  171   a ,  171   b . The longitudinal key pen portion  165   b  protrudes in the main liquid flow direction DL approximately up to a level of the liquid interface  115 , for example less than approximately 5 mm from, or approximately level with, the liquid interface edge  116  along the second interface dimension d 2 . The longitudinal key pen portion  165   b  may extend over a length KL (e.g. see  FIG. 21 ) from the base  169   a  of at least approximately 15, at least approximately 20, or approximately 23 mm. The interface structure  105  includes a pair of pen base holes  185  for a corresponding pair of key pens  165 , at opposite sides of the liquid channel  117 , in the recess base  169   a.    
     In one example, the base portion  183  includes at least one datum  187  to facilitate correct positioning of the key pen  165  in the pen base hole  185  of the interface structure  105  of the supply apparatus  101 . The key pen datums  187  may facilitate determining and fixing a rotational orientation of the key pen  165  with respect to the base wall  169   a . In turn, the base  169   a  may include at least one counter datum  189  at the pen base hole  185 . The number of datums  187  of the key pen  165  and/or counter datums  189  of the key pen hole  185  may determine the maximum number of predetermined rotational orientations. 
     Examples of different predetermined rotational orientations of the key pen  165  are illustrated in  FIGS. 29-32 . Each predetermined rotational orientation of the key pen  165  in the interface structure  105  may be associated with a correspondingly shaped key slot  167  of a corresponding receiving station  107 . Hence, each rotational orientation can be associated with a specific color or type of print liquid in the container  103 . A plurality of datums  187  may be provided directly at the base  169   b  of the key pen  165 , around the base portion  183  in a plane parallel to the first and third interface dimensions d 1 , d 3 . In turn, the pen base hole  185  may include at least one counter datum  189  to facilitate aligning the at least one key pen datum  187  to the at least one counter datum  189 . 
     In the illustrated example, the base portion  183  and the base wall  169   a  both include a plurality of matching datums  187 ,  189 . In other examples, the number of datums  187  on the key pen  165  can be different than the number of counter datums  189  on the base wall  169   a  while still facilitating the predetermined number of rotational orientations of the key pen  165 . In one example the base wall  169   a  includes only one datum  189 , and the corresponding key pen  165  includes a plurality of datums  187 , or vice versa, the key pen  165  includes only one datum  187  and the base wall  169   a  includes a plurality of datums  189 . In examples that use a plurality of datums  187  and/or counter datums  189 , these datums  187 ,  189  can be provided at regular positions, for example at equal distances from each other around a circle. In the illustrated examples the datums  187  and counter datums  189  are embodied by teeth, whereby each key pen datum tooth is associated with a correspondingly shaped space between adjacent counter datum teeth. Correspondingly,  FIGS. 29-32  illustrate orientations of an example key pen  165  with pluralities of datums  187  around the key pen  165 , wherein the datums  187  are in the form of teeth, while  FIG. 33  illustrates a pen hole  185  in a base  169   a  with only a single counter datum  189 , here also in the shape of a tooth that is to engage between two key pen datum teeth  187 . The distal ends of the key pen datum teeth  187  will engage the internal edge  185   a  of the pen hole  185  also where there are not counter datum teeth. This to illustrate that the rotational orientation of the key pen  165  can be chosen and fixed with different numbers of datums  187 ,  189 . 
     According to the same principle, the key pen base portion  183  could be provided with only a single datum  187  as illustrated in  FIG. 34  whereby the pen hole  185  may be provided with a plurality of counter datums  189 . The key pen  165  may be aligned in predetermined rotational orientation by aligning its datum tooth  187  between two counter datums  189  of the pen hole  185 . 
     In other examples, the datums  187  and/or counter datums  189  could be defined by visual marks, other marks, corners, ribs, cuts, cut outs, undulations, or other suitable features, whereby again the opposite datum and counter datum may be provided in different suitable numbers. In further examples outer edges of the base portion  183  and/or inner edges of the pen hole  185  may have the contour of a polyhedron having three, four, six, twelve or any number of faces around the longitudinal pen axis Ck, to similarly allow for a predetermined number of different rotational orientations of the key pen  165  with respect to the base wall  169   a , whereby in this disclosure the outer faces and corners of the polyhedron may be considered datums  187 ,  189 , respectively. 
     In one example the key pen  165  and/or base wall  169   a  include at least twelve datums, which would facilitate attaching the same key pen  165  in at least twelve different rotational orientations, with respect to the base wall  169   a , and in turn associating the same interface structure features with twelve different liquid types. In other examples, for example six, three, sixteen, twenty-four or different numbers of datums  187  and/or counter datums  189  could be used, for example for association with different numbers of liquid types. 
     In one example, the base portion  183  includes a flange or disc  186  that defines the key pen base  169   b , from which the rest of the cylindrical base portion  183  extends backwards, along the needle insertion direction, and the longitudinal key pen portion  165   b  protrudes forwards from the disc  186 , along the main liquid flow direction DL in assembled condition. In one example, the pen axis Ck approximately intersects the middle of the disc  186 . The disc  186  is adapted to fit in the key pen base hole  185  in the recess base  169   a . The disc edge may include the datum teeth regularly positioned around the disc edge and at equal distances from each other, as described earlier. In assembled condition a back of the disc  186  and the datum teeth, at the opposite side of the disc  186  with respect to the key pen base  169   b , may support against a disc support surface  184  in a wall that defines the recess base  169   a , best illustrated in  FIGS. 21 and 24 . The support surface  184  is recessed in the recess base  169   a  to facilitate positioning of the pen base  169   b  (e.g. the disc  186 ) and counteracts against an inward pushing force of the key pen  165  on the support surface  184  for example when the key pen  165  pushes against an opposite actuator such as the rod  179 . 
     In further examples, the base portion  183  includes at least one snap finger  191  at its back end  188  to plug and snap the key pen  165  to the interface structure  105 . In the illustrated example, the back end  188  of the base portion  183  includes two opposite snap fingers  191 , best seen perhaps in  FIGS. 27 and 28 . The snap fingers  191  may include abutting edges  191   b  that abut against a further support wall surface  191   c  of the interface structure  105 , for example that is offset from the base  169   a  in a backwards direction. In the illustrated example, the support wall  191   c  extends between the base  169   a  and the back wall  154   d . Hence, the disc  186  and the snap fingers  191  of the key pen  165 , and said support surfaces  184 ,  191   c  of the interface structure  105 , may retain or clamp the key pen  165  with respect to the interface structure  105  in both directions along the pen axis Ck. In turn, protruding datums may fix the rotational orientation of the key pen. 
     In other examples, the key pen  165  may be attached in a different way to a wall of the interface structure  105  or may be integrally molded with a wall of the interface structure  105 . In one example, the base portion  183  may include a screw thread to screw the key pen into the base  169   b.    
     The protruding longitudinal key pen portion  165   b  is adapted to provide at least one of a keying function, guiding function, and actuating function. Regarding the latter function, the key pen  165  may be adapted to actuate upon an actuator, such as at least one of a mechanical actuator and switch that are provided in the receiving station. In certain examples the protruding longitudinal key pen portion may only facilitate two of said functions, for example only guiding and actuating, not keying, or only keying and guiding, not actuating. In other examples the key pen only guides or actuates without exercising the other functions such as keying. In again another example the key pens are used for relatively precise guiding of the liquid interface  115  with respect to a liquid needle of the receiving station, whereby some or all of the guide surfaces  141 ,  141   b ,  145 ,  143 ,  143   b ,  147  described above may be altered or omitted. 
     For example, the key pen  165  is associated with a supply apparatus of a certain color or type of print liquid and is adapted to pass through a corresponding receiving key slot  167  (e.g. see  FIGS. 20, 21 ). In a first example, a key pen  165  is shaped to pass through a key slot  167  of a first receiving station of a printer, and is to be blocked by a non-matching key slot  167  of another receiving station of the same printer to avoid color or liquid-type mixing. In a second example, a single shape key pen  165  may be adapted to pass through different key slots  167  associated with different liquids, of respective different receiving stations of the same printer, whereby the key pen  165  has only a guiding and/or actuating function but not necessarily a color/type keying function. The first example may be referred to as a discriminating key pen and the second example may be referred to as an actuating key pen or master key pen. For example, master key pens could be used for service fluids to connect to different receiving stations of a single print system, or simply for alternative supply apparatuses. Actuating key pens could be applied in supply apparatuses for monochrome print systems with only a single receiving station, for the purpose of actuating an actuator only, without needing color discrimination. Different types of key pens may be applied for different functions. 
     In line with the previously mentioned first example, a set of supply apparatuses  101  may be provided that includes a similar interface structure  105  and container  103  construction for each supply apparatus, wherein one of the containers  103  contains a different liquid type than another one of the containers  103  and the corresponding interface structures  105  have different key pens configurations, for example key pens  165  in different rotational orientations around the respective pen axis Ck, to inhibit installation to a receiving station that does not correspond with the particular liquid type. For example, different supply apparatuses  101  such as illustrated in  FIG. 5  may include different liquids and different corresponding key pen cross-sections and/or different key pen orientations. 
       FIGS. 29-32  illustrate examples of key pen shapes, as viewed along the longitudinal axis Ck of the pen straight onto the key pen base  169   b , wherein the cross-sectional key-shapes along the longitudinal key pen portion  165   b  are the same, yet the rotational orientations are different. When installed into the interface structure the plane of the cross section may be parallel to the first and third interface dimension d 1 , d 3 . Pairs of key pens may be provided in each corresponding interface structure wherein the key pens of the pair may have the same rotational orientation, or a different orientation, with respect to each other, and the key slots of the corresponding receiving stations have corresponding configurations. The different orientations of  FIGS. 29-32  may be associated with different liquid types and with matching rotational orientations of corresponding key slots  167 . 
     In the examples of these figures, each key pen cross section is in the form of a Y, for example to pass through a matching Y-shaped key slot  167 . Other example cross-sectional key-shapes may be in the form of a T, V, L, I, X or one dot or a series of dots or other geometrical shapes. In this description, a V-shape includes an L-shape and an X-shape includes a +-shape, for example because the key pen  165  may be rotated. The key-shapes may match corresponding Y, V, L, I, T, X-shaped key slots shapes. For example, the cross-section of the protruding key pen portion  165   b  may correspond to a Y, V, L, I, T, X or the like, but may have interrupted portions with notches in between the actuating surface areas  168 . For example, the cross-section of the protruding key pen portion  165   b  may generally follow the Y, V, L, I, T, or X-shaped contour, for example corresponding to the respective key slot  167 , in either a continuous or in an interrupted fashion, whereby an embodiment that is interrupted may have separate distal actuating surface areas  168  with spaces in between. It is also noted that while the Y-shaped key pens  165  may be associated with Y-shaped key slots  167 , in some instances also V- (e.g. L-), I-, or dot shaped key pens  165  may be used to pass through a Y-shaped key slot  167  while still actuating on the respective actuator such as a rod  179  and/or switch behind the key slot  167 . 
     The longitudinal key pen portions  165   b  of  FIG. 27  has three longitudinal wings  165   d  or flanges that extend along, and away from, the pen axis Ck. Each wing  165   d  defines a leg of the Y. The wings  165   d  extend along the pen axis Ck in the direction of the second interface dimension d 2 . The wings  165   d  extend away from each other, away from the pen axis Ck, thereby providing for the Y-shaped cross section. An intersection Ck of the three wings  165   d , i.e. in the middle of the Y, may be located approximately on the pen axis Ck. In other examples the intersection Ck of the wings  165   d  may be offset from a center of the key pen base  169   b , and/or offset from a pen axis Ck. Similarly, a key pen having a V-shaped cross-section may have an intersection in or near the center of the key pen base  169   b  or key pen hole  185 , or away from the center. 
     For example, the key pen  165  includes an actuating surface area  168  to actuate upon a counterpart actuator of the receiving station, such as the rod  179  or a switch, whereby the counterpart actuator may be provided behind the key slot  167  to facilitate that only matching key pens  165  may actuate upon the actuator. The actuating surface area  168  may be provided at the distal end of the longitudinal key pen portion  165   b . As clearly viewable from  FIGS. 19, 21 and 35 , in certain examples the outside ends of the actuating surface areas  168  of the wings  165   d  define the actuating surfaces  168  because these surfaces  168  engage the actuator rod&#39;s edges at insertion of the interface structure  105  into the receiving station  107 . 
     In  FIG. 35  the actuating surfaces  168  are diagrammatically indicated by circles in dotted lines at the position where the key slot  167  and the edge of the rod  179  (also in dotted lines) overlap. For example, when the hollow rod  179  is actuated by a V- or Y-shaped key pen  165  there are two or three, respectively, separate actuating surface areas  168  at distances from each other, near the outer ends of the legs of the V or Y, respectively, at a distance from a central or longitudinal pen axis Ck, that engage the rod  179 . One actuating surface area  168  may be sufficient to act upon the actuator. 
     In another example there may be a center actuating surface area  168   c . A receiving station may include a rod portion, switch or lever that is actuatable by the center actuating surface area  168   c . In certain example such center actuating surface area  168   c  could be for a master key pen, as will be explained below. Any key pen  165  of suitable configuration and having any of said actuating surface areas  168  can facilitate mounting and unmount of the supply apparatus  101  with respect to the receiving station. 
       FIG. 36  illustrates another example of a cross section of a key pen  265 , perpendicular to its longitudinal axis Ck. At a minimum, the key pen  265  may include a single cylindrical or beam-like protruding longitudinal pin  165   e  with an actuating surface area  168   a  at its distal end to push the rod  179 . The pin  165   e  and its actuating surface area  168   a  may be positioned to pass through a corresponding Y- or V-shaped key slot  167  and to engage the respective actuator, such as the circular push edge of the rod  179 . For differently oriented key slots  167 , the pin  165   e  will need to be positioned differently with respect to the base  169   b  to pass through these differently oriented key slots  167 . Hence a key pen  165  comprising, or consisting of, a single cylindrical pin  165   e  in a predetermined position may provide for a liquid-type-discriminating key pen, sufficient to trigger an actuator and facilitate installation to the receiving station. 
     In other examples, also illustrated in  FIG. 36 , further pins  165   f  may be provided to pass through a respective key slot and engage the actuator  179 , as illustrated with dotted circles  165   f . Hence, one or more cylindrical, pin-shaped or beam-like longitudinal key pens  165   e ,  165   f  may protrude from the base  169   b , along the pen axis Ck to pass through a key slot  167  and act upon a respective actuator, such as a rod  179  or switch, with respective actuating surface areas  168   a ,  168   b . Alternatively, the protruding key pen portion may be Y- or V-shaped over a substantial portion of its length and then may diverge towards different actuating surface areas  168   a ,  168   b , or may converge towards a single actuating surface area  168   a . Again, a master or center protruding pen  165   g  may be provided, for example of extended length to reach an inside base or the rod  179 . 
       FIG. 37  illustrates an example side-view of such key pen  265  with one or more of such separate actuating surface areas  168   a ,  168   b , having respective protruding pins  165   e ,  165   f  that may be suitable to pass through key slots and act upon an actuator. In certain examples the longitudinal key pen portion  165   e ,  165   f  may include plastic or metal pins protruding from the base wall  168   a ,  168   b . The length of the pins  165   e ,  165   f  between the base  169  and the actuating surface area  168   a ,  168   b  may be approximately the same as the earlier mentioned protruding key pen portions  165   b  of  FIGS. 27-32 . 
     Referring to  FIGS. 37A, 35 and 36 , a “master” key pen  265  may include at least one pin  165   g  with an actuating surface area  168 C that is positioned to pass through differently shaped or oriented key slots  167  associated with different types or colors of liquid, for example through a center of such key slot  167 . For example, such at least one pin  165   g  could be provided at a predetermined position, so that it passes through multiple differently shaped or orientated Y- or V-shaped key slots  167  of multiple receiving stations associated with different liquid types and/or colors, for example a center position with respect to its base or the key slot  167 . The pin  165   g  may extend approximately parallel to the main liquid flow direction DL. The pin  165   g  may be provided at a location that corresponds with a center of a Y-shaped key slot  167 , where the three legs of the Y intersect, so that it can pass through the centers of differently oriented Y-shaped key slots  167 . 
     In one example, as illustrated in  FIG. 37A , a master key pen  265 B extends further than the interface front  254  and/or the liquid interface edge (e.g. edge  116  in other figures), as diagrammatically illustrated by the contour of a corresponding recess  271 . For example the master key pen  265 B protrudes at least 5 mm, at least 10 mm, at least 15 mm or at least 20 mm beyond the interface front  254  or liquid interface edge  116  as viewed along the third interface dimension d 3 . Hence, the key pen  265 B may have a length of at least approximately 30, at least approximately 35, at least approximately 40 or at least approximately 45 mm, for example as measured between its base  269  and its actuating surface area  168   c . At insertion of the interface structure into the receiving station, the extended master key pen  265 B may protrude inside the hollow rod  279  until the distal actuating surface area  168   c  of the pen  265 B engages an inner wall  279 A of the rod  279  whereby the master key pen  265 B may push the rod inwards by pushing against that inner wall  279 A, for example to trigger the hook  161 . The additional length beyond the interface front  254  or liquid interface edge may serve to span the distance between the front edge of the rod  279  and said inner wall  279 A upon which the master key pen  265 B acts. In other examples, a master key pen may be shaped differently than a pin, and/or may engage other types of actuators. Having a master key pen that does not discriminate between certain receiving stations could be useful for color or type independent liquid supply apparatuses such as service supplies with service liquid, or to save costs, or for other reasons. 
     In an example, the master key pen does not discriminate between receiving stations in a set of receiving stations, but it discriminates between different sets of receiving stations. In again other examples the key pen  265 ,  265 B may include an extended pin similar to the current extended pin  165   g  but it does not serve as a master key pen. An extended color or liquid type discriminating key pen  265 ,  265 B could be provided. In other examples, a longer not-pin-shaped key pen like the master key pen  265 B may be used that has a similarly extended shape, for example to engage an inner wall  179 A of a rod  179  or any other suitable actuator component. 
       FIG. 38  illustrates again a different example of a cross section of a key pen  265 C. The cross section is V-shaped. The key pen  265 C includes a longitudinal key pen portion  165   g , with two wings  165   d , that match part of the Y-shaped key slot  167  as indicated in  FIG. 35 , suitable for passing through said Y-shaped key slot  167  and actuating the rod  179  for example with two corresponding external actuating surface areas  168   d . The V-shaped pen  265   c  may be relatively flatter along its longitudinal axis as compared to the Y-shaped pens  165 . Accordingly, the key pen shape may be “reduced” while still performing its function. In an example where a Y- or V-shaped key slot is used also an I-shaped key pen cross section could work, or at least one dot-shaped cross section or any other cross section that matches part of a V or Y and touches the edge of the rod  179  could work. 
       FIG. 39  illustrates another diagrammatic example of a key pen  365  in a recess  371 , protruding from its base  369 . This key pen  365  does not extend exactly parallel to the second interface dimension d 2  or the main liquid flow direction DL. The key pen  365  extends along its longitudinal axis Ck, but not exactly parallel to the second interface dimension d 2 . The longitudinal axis Ck is tilted with respect to the main liquid flow direction or second interface dimension d 2 . Here, the longitudinal axis Ck of the key pen  365  extends approximately in the main liquid flow direction DL, but it is tilted at an angle with said main liquid flow direction DL, while still allowing insertion through a key slot and actuating an opposite actuator of the receiving station. The longitudinal distance between the base  369  and the actuating surface area  368  of the key pen  365  may be at least approximately 10 mm, at least approximately 12 mm, at least approximately 15 mm, at least approximately 20 mm, or at least approximately 23 mm. It is again noted that certain margins and tilt angles of the key pen  165  with respect to the main liquid flow direction are allowed within the scope of this disclosure. 
       FIGS. 29-39  illustrate different examples of key pens that may be used for any of the interface structures of this disclosure, and that may be suitable to actuate certain actuators provided in the receiving stations. While in these examples single key pens are illustrated, the key pens may be provided in pairs, at both lateral sides of the liquid output, as illustrated in other figures. In turn, the corresponding actuators, when actuated by these key pens, may trigger at least one of (i) certain retention mechanisms to retain the supply apparatus to the receiving station and/or (ii) a pump switch, and/or (iii) data communication, and/or (iv) other actions. Any of the example key pens of this disclosure may have a length along a pen axis Ck, between a key pen base and an actuating surface area, of at least approximately 10 mm, of at least approximately 12 mm, of at least approximately 15 mm, at least approximately 20 mm, or at least approximately 23 mm whereby the actuating surface area may be approximately level with the liquid output edge or a front of the interface structure. That said, an example extended (e.g. master) key pen version (e.g.  FIG. 37A ) may be at least approximately 30 mm, at least approximately 35 mm, at least approximately 40 mm or at least approximately 45 mm. 
       FIG. 40  illustrates a kit  100  of components for construing a supply apparatus  101  according to a further example of this disclosure. The kit  100  includes a container  103  to hold liquid. The kit  100  includes an interface structure  105 . The kit  100  includes liquid interface components  114  for a liquid channel of the interface structure  105 . The kit  100  includes key pens  165  for attachment to the interface structure  105 . The kit  100  includes an integrated circuit  174  for attachment to the interface structure  105 , including a contact pad array. The kit  100  includes at least one liquid interconnect element  134  to connect a liquid input  124  of the reservoir connecting liquid channel portion  129  of the interface structure  105  with the container  103  to allow liquid to flow between the container  103  and the liquid channel  117 . The kit  100  may further include a mechanical connection structure  106  to mechanically connect the interface structure  105  with the container  103 . The mechanical connection structure  106  may also serve as a strengthening member along a respective side  125  of the supports structure  135 , at least in assembled condition. The respective side  125  can be a back of the container  103 . 
     The at least one container  103  includes an at least partially collapsible reservoir  133  and a support structure  135 . The container  103  may further include a label  135   a  whereby information on the label may indicate an installation orientation of the supply apparatus  101  and/or where to push the supply apparatus  101  into the receiving station. To that end the label may at least partially extend at a back  125  of the support structure  135 . The support structure  135  may be a folded carton box-shaped structure that holds the reservoir  133 . The support structure  135  includes a projecting portion  123  that extends near a front  131  of the support structure  135 , and a back  125 , opposite to the front  131 . An opening  113 A (not visible in this view) is provided in a bottom  113  of the support structure  135 , near the back  125  of the support structure  135 , to allow for the reservoir connecting channel portion  129  and input  124  of the liquid channel of the interface structure  105  to pass through the support structure  135 , to connect to the reservoir  133 . In assembled condition the reservoir connecting channel portion  129  may extend through the bottom opening  113 A into the support structure  135  while the rest of the interface structure  105  may project downwards away from the bottom  113 , over an extent in this disclosure defined by the first interface dimension d 1 . The kit  100  may further include at least one liquid interconnect element  134  to facilitate connection between the reservoir  133  and the reservoir connecting channel portion  129 , near the bottom  113  and back  125  of the reservoir  133 . The liquid interconnect element  134  may include an interconnect spout attached to a neck of the reservoir  133 , or be integral to the reservoir  133 . 
     The support structure  135  is illustrated in an open condition wherein backside flaps are open to allow the reservoir  133  to be placed in the support structure  135 , whereby the interface structure  105  and/or reservoir  133  may be connected to the support structure  135  with the aid of a mechanical connection structure  106 , extending near the back  125  and bottom opening  113   a , along the back and bottom opening  113   a . The interface structure  105  and/or reservoir  133  extend partially through the bottom opening  113   a . The mechanical connection structure  106  may include at least one clamping profile to clamp to the support structure  135  at assembly. In assembled condition the mechanical connection structure  106  may strengthen the back  125  of the supply apparatus  101 , for example to facilitate pushing the back wall  125  at insertion and ejection. In assembled condition the mechanical connection structure  106  may be substantially L-shaped at least when viewing its cross-section in the center plane CP (e.g. see  FIG. 9 ) as viewed along the third container dimension D 3 . 
     The mechanical connection structure  106  largely extends between the reservoir  133  and the support structure  135 , along the respectively first and back walls  113 ,  135 , at the inside of the support structure  135 , at least partially along the opening  113   a  and at least partially around the interconnect element  134 , for example between flanges of the interconnect element  134 . The mechanical connection structure  106  may include at least one wedge to clamp the reservoir and support structure walls, for example by wedging respective walls of the support structure  135  and reservoir  133  between the mechanical connection structure  106  and flanges of the interconnect element  134 . 
     The liquid interface components  114  of the example kit of  FIG. 40  may include a seal  120 , for example a seal plug, and ball valve components, to be placed at the downstream end of the liquid channel  117  of the interface structure  105 , to form part of the liquid interface  115 . 
     In one aspect, this disclosure provides for an intermediate subassembly of components of the supply apparatus  101  without interface structure  105 , such as a container comprising a print liquid reservoir  133  and a support structure  135 . A set of components to assemble the container  103  may be provided. 
     The reservoir  133  is to be placed in the support structure  135  of  FIG. 40 , whereby in folded and mounted condition the support structure  135  may provide for a box or cubicle shaped structure to extend at least partially around the reservoir  133 , whereby the mounted reservoir and support structure define the container  103 . The container  103  has first, second and third container dimensions D 1 , D 2 , D 3 . The support structure  135  is adapted to at least partially surround and support the reservoir  133  and to provide stiffness to the container  103 . The reservoir  133  includes a bag to hold the print liquid, being at least partially flexible to collapse while print liquid is withdrawn from the reservoir  133 , the at least one wall of the bag being configured to inhibit fluid exchange. The reservoir  133  includes, or is to be attached to, an interconnect element  134 ,  434 , for example through a reservoir neck. The neck includes an opening into the bag, to output print liquid from the bag. A largest internal diameter of said neck can be less than half the third and/or second container dimension D 3 , D 2 . In a filled state, when mounted into the support structure  135 , starting at the neck, at least approximately two thirds, three fourths, or four fifths of the bag&#39;s length projects along the second container dimension D 2  away from the neck, and a smaller volume  423 A may extend at the opposite side  425  of the neck, e.g. the back side. In the mounted and folded condition, the support structure  135  includes approximately perpendicular walls defining said first, second and third container dimension, D 1 , D 2 , D 3 , the first and second dimension D 1 , D 2  being more than the third dimension D 3 , wherein a first wall  113  defining the second and third dimension D 2 , D 3  includes an opening  113   a  (e.g. see  FIG. 22 ) adjacent said neck of the reservoir  133  when positioned in the support structure  135 , to allow connection of another fluid structure to the neck. Such other fluid structure can be the interface structure  105 . In the mounted and folded condition of the support structure  135 , the opening  113   a  in the first wall  113  is provided adjacent another wall  125  adjacent the first wall  113 , the other wall  125  being parallel to the first and third dimension D 1 , D 3 . 
     In one aspect, this disclosure relates to a method of assembling different components to obtain the supply apparatus  101 , wherein at least one of the components is collected after a previous usage. The at least one collected component can be any of the different example supply features within the scope of this disclosure and/or described in this disclosure. For example, after exhaustion of the supply apparatus  101 , the interface structure  105  can be separated from the container  103 . For example, after such collection, the key pens  165  and the single molded base structure  105 - 1  of the interface structure  105  can be separated. Then, one of (i) newly manufactured key pens  165 , or (ii) previously used and collected key pens  165  may be connected to the base structure  105 - 1  in an orientation that corresponds to the desired receiving station and liquid type. For example, similar to the original assembly before first usage, the new or re-used key pen  165  may fit in a key slot  167  of the base structure  105 - 1 . For example, datums  187  and/or counter datums  189  may be used to facilitate correct rotational positioning. The interface structure  105  may then be connected to a filled new-built reservoir  133  or to a refilled re-used reservoir  133 . The reservoir  133  and/or support structure  135  can be newly manufactured before filling and then connected to the recovered base structure  105 - 1 , or, at least parts of the reservoir  133  and/or support structure  135  could be recycled before connection to the base structure  105 - 1 . Hence the recycled base structure  105 - 1  may be re-purposed for a different liquid type, a different printer platform, a different liquid volume, etc. as compared to the first usage of the same base structure  105 - 1 . The original integrated circuit  174  could also be exchanged, refurbished, or replaced with a new integrated circuit  174  to match said desired liquid type, station and/or platform. 
       FIG. 40A  illustrates a diagram of an example of an unfilled reservoir  133 A. The unfilled reservoir  133 A may be a flexible bag that may be substantially flat in the unfilled, empty state. For example, the bag in empty state may be largely defined by two opposite films connected or folded at short outer edges of the unfilled bag. For example, the outer edges may be folded edges between the two connected opposite films or two separate opposite films may be welded. The flat unfilled bag may have a length LA and width WA. In a filled state, that is, in an at least partly expanded state of the reservoir  133 A, the length LA and width WA may be difficult to distinguish and for example do not correspond to, nor extend along, any of the earlier mentioned container dimensions D 1 , D 2 , D 3 . 
     The reservoir  133 A includes an interconnect element  134 A, for example to connect to a reservoir connecting portion of a liquid channel of an interface structure or cap. The interconnect element  134 A may be a neck of the reservoir  133 A. The interconnect element  134 A may have an inner liquid channel, and outer flanges such as illustrated in  FIG. 22  to facilitate connection of the support structure, the mechanical connection structure  106 , and the interface structure. The interconnect element  134 A may be offset from a center of the reservoir  133 A unfilled and flat state. The interconnect element  134 A may be offset from a middle of the width WA and/or offset from a middle of the length LA of the reservoir  133 A in unfilled and relatively flat state, for example relatively adjacent a corner of the flat unfilled reservoir  133 A. The interconnect element  134 A may be connected to one of the opposite films. 
       FIG. 41  illustrates a supply apparatus  401  wherein the container  403  includes an at least partially collapsible reservoir  433  wherein a projecting portion  423  of that reservoir  433  protrudes beyond a liquid interface edge of the interface structure  405 , in a main liquid flow direction DL. In the illustrated example, no separate support structure, such as a tray or box, is provided. The apparatus  401  of  FIG. 41  can be an intermediate product for further assembly, or a finished product for direct connection with a receiving station. For example, where the supply apparatus  401  is a finished product, certain stiffening members may be provided along, or integral to, the reservoir  433 . The container  403  includes a fluid interconnect element  434  to connect to the interface structure  405 . Here, the interface structure  405  is connected to, and protrudes from, the liquid interconnect element  434 , rather than directly from a reservoir bottom wall. The extent of the first dimension d 1  of the interface structure  405 , which determines both the height and the direction of the height, may be measured between (i) a deepest bottom  413  of the projecting portion  423 , or a distal end of the liquid interconnect element  434 , and (ii) the distal side  437  of the interface structure  405 , along the direction of the first dimension d 1 , D 1 . In another definition the first interface dimension d 1  may be determined by a distance between an external distal side  437  of the interface structure  405  and a front top edge  454   b  just above the liquid interface. Even if the interface structure  405  does not protrude directly from a bottom face  413  of the container  403 , the height of the interface structure  405  may be determined by the height between the distal side  437  and the front edge  454   b , within which the interface components are included such as the needle receiving liquid channel portion and other interface components such as at least one of the integrated circuit contact pads, key pens, guide features, etc. Again, as also illustrated in  FIG. 26 , the interface structure  405  may include an intermediate channel portion with liquid input opening to receive liquid from the container, the intermediate portion and input protruding beyond the profile height of the interface structure  405 , partly into the liquid interconnect element  434  or the container  403 . 
       FIGS. 42-47  illustrate examples of supply apparatuses of this disclosure in different operational orientations, whereby for each example the interface structure is positioned differently with respect to the container. For example, in  FIGS. 42 and 43  the interface structure projects from a lateral side of the container. In  FIG. 44  the interface structure projects from a first side of the container, at a distance from opposite sides adjacent to, and at a straight angle with, said first side. In  FIG. 45  the interface structure projects from a wall of the container near a front of the container, at a distance from the back whereby the liquid interface extends at the front. In  FIGS. 46 and 47  the interface structure projects upwards from a top of the container. These different orientations and configurations may be facilitated because the outputs of certain example collapsible liquid bag reservoirs of this disclosure can be oriented and located in any direction, with little influence of gravity. 
     In the example supply apparatus  501 A of  FIG. 42 , the interface structure  505 A protrudes from a lateral side  513 A of the container  503 A, in the first interface dimension d 1 , when installed. Here, the first container dimension D 1  and the first interface dimension d 1  extend horizontally, although the supply apparatus could be tilted as compared to the illustrated orientation. The needle insertion direction extends approximately horizontally, along the corresponding second dimensions D 2 , d 2 , into the page, at straight angles with the first dimensions D 1 , d 1 . The supply apparatus  501 A of  FIG. 42  may include a projecting portion  523 A of the container  503 A that projects beyond the liquid interface  515 A, along said second dimensions D 2 , d 2 , out of the face of the page. Correspondingly, the third dimensions D 3 , d 3 , which in other examples have been referred to as a “width” of the container and interface structure, respectively, extend vertically for the example orientation and supply apparatus of this figure. 
     In the example supply apparatus  501 B of  FIG. 43 , the interface structure  505 B protrudes from a lateral side  513 B parallel to the first interface dimension d 1 , which in the drawing is approximately horizontal, wherein again “approximately” is meant to include a tilted condition with respect to exactly horizontal as explained above. In this example, the needle insertion direction of the respective liquid channel portion near the liquid interface, and the main liquid flow direction, may extend approximately vertical. The projecting portion  523 B of the container  503 B projects beyond the liquid interface  515 B of the interface structure  505 B, in the main liquid flow direction DL, along the second dimensions D 2 , at approximately straight angle with the first dimension D 1  of the container, and over a projection distance PP that may be several times the second interface dimension d 2 . In one example scenario, the supply apparatus  501 B of  FIG. 43  can be hung onto a receiving station of a host printer in its illustrated orientation, for example onto a fluid needle protruding at a side of the printer in an upwards direction, whereby the key pens of the supply apparatus protrude downwards to actuate upon an actuator of the receiving station. The supply- and printer-side key and retention mechanisms, if any, can be adapted to accommodate a vertical installation position. 
       FIG. 44  illustrates a diagram of another example supply apparatus  501 C, with an extended container volume  523 C 2 ,  523 C 3 . The interface structure  505 C projects outwards with respect to a bottom  513 C of the container  503 C, at a distance PP, PP 2  from both the front  531 C and back  525 C, respectively, of the container  503 C. For example, the interface structure  505 C may project from a bottom  513 C of the container  503 C near a middle of the bottom  513 C of the container  503 C between the front  531 C and back  525 C of the container  503 C. The container  503 C includes a first projecting portion  523 C projecting beyond the liquid interface  515 C along the main liquid flow direction DL, over a projection extent PP. In this example, the container  503 C includes a second projecting portion  523 C 2  opposite to the first projecting portion  523 C projecting in the opposite direction with respect to the main liquid flow direction DL. In the illustrated example the second projecting portion  523 C 2  extends beyond a back  526 C of the interface structure  505 C, over a second projection extent PP 2 . In addition, the second projecting portion  523 C 2  may further include a further volume extension  523 C 3 , which in the illustration projects downwards but which may also project upwards or in any other direction. In one example, the second projecting portion  523 C 2  facilitates adding volume to the container  503 C. In an installed condition of the supply apparatus  501 C, the second projecting portion  523 C 2  may project outside of the contour of a printer receiving station. In fact, different types of volume projections/extensions  523 C 2 ,  523 C 3  may be added to any container of this disclosure, in any direction, for example to expand the volume or shape of the container. In the example of  FIG. 44 , these volume extension is integral to the container. In other examples volumes may be connected by way of a separate fluidic connection to the container. 
     Two different configurations of liquid channels  517 C 1 ,  517 C 2  are illustrated in  FIG. 44 . Both configurations are possible within the scope of this disclosure. A first one  517 C 1  of the liquid channels  517 C 1  includes a reservoir connecting portion at an angle with a needle receiving portion wherein the liquid channel  517 C 1  connects at the top of the interface structure  505 C, at least in the illustrated orientation. Another example liquid channel configuration  517 C 2  may have a reservoir connecting portion near a back  526 C of the interface structure  505 C, to connect to the volume extension  523 C 3 , at least in the illustrated orientation, wherein the reservoir connecting portion need not be at an angle with the needle receiving portion. A neck or and/or interconnect element of the reservoir may connect to the liquid channel  517 C 2  near a back  526 C of the interface structure  505 C. In other examples, differently configured volume extensions  523 C 3  may be provided, which may be connected to the respective liquid channel at another side of the interface structure  505 C. 
     In another example the container  503 C has a single extended cuboid shape along the second container dimension D 2  with first and second projecting portions  523 C,  523 C 2 , each projecting portion  523 C,  523 C 2  projecting beyond the back and front of the second interface structure dimension d 2 , but without said further volume extension  523 C 3 . In another example the interface structure  505 C may include certain extended relatively rigid supports elements that project in a backwards direction under such second projecting portion  523 C 2 , for example to mechanically support the weight of the filled second projecting portion  523 C 2  that in installed condition may extend outside of the receiving station. 
       FIG. 45  illustrates a diagram of another example supply apparatus  501 D wherein the liquid interface  515 D is provided approximately near or level with the front  531 D of the container  503 D, under the bottom  513 D of the container  503 D. The supply apparatus  501 D includes a second projecting portion  523 D 2 , projecting towards the back  525 D of the container  503 D beyond a back  526 D of the interface structure  505 D over a second projection extent PP 2  in a direction parallel to the second dimension D 2 , opposite with respect to the main liquid flow direction DL, for example similar to  FIG. 44 , but with the difference that there is no first projecting portion ( 423 C) that projects beyond the liquid interface  515 D. Similar to  FIG. 44 , the second projecting portion  523 D 2  of  FIG. 45  may include further extensions ( 523 C 3 ) in other directions. This supply apparatus  501 D may for example facilitate receiving stations of more shallow depth, or provide for an alternative design as compared to examples of this disclosure. In another example, the supply apparatus  501 D of  FIG. 44 or 45  may facilitate an approximately vertical installation whereby the second projecting portion  523 D 2  projects at least partly out of, and upwards from, the respective receiving station or printer. 
       FIGS. 46 and 47  illustrate other example supply apparatuses  501 E where for each apparatus  501 E the interface structure  505 E projects from a top  531 E upwards, in installed orientation. In one example a receiving station  507 E may be connected to the interface structure  505 E by manually moving the receiving station  507 E towards the interface structure  505 E, as illustrated in  FIG. 47 , and sliding it over the interface structure  505 E to establish fluidic connection. In certain examples the container  503 E may have a volume larger than approximately 500 ml, larger than approximately 1 L or larger than approximately 3 L. Where the container  503 E has such large volume, there may be reasons to choose for a system where the receiving station  507 E is to be moved towards the supply apparatus  501 E, rather than the supply apparatus towards the receiving station as in other examples of this disclosure, because of the weight of the supply apparatus  501 E in filled state, and/or because of its relatively large volume. In the illustrated examples, the third dimension D 3  of the container  503 E is significantly greater than the third dimension d 3  of the interface structure  505 E. In certain examples the third dimension D 3  of the container  503 E is at least two times the third dimension d 3  of the interface structure  505 E, or at least three times the third dimension d 3  of the interface structure  505 E. 
     It will be understood that, while in the drawings of  FIGS. 42-47  certain components of the supply apparatuses have been moved and/or rotated along straight axes and straight angles with respect to the earlier disclosed supply apparatuses of earlier figures, such as the supply apparatus of  FIGS. 8 and 9 , in other similar examples that are in line with  FIGS. 42-47 , the respective supply apparatus components may be tilted at a non-straight angles and also the respective dimensions D 1 , d 1 , D 2 , d 2 , D 3 , d 3  may be tilted at corresponding non-straight angles. Also, the supply apparatus of  FIGS. 8 and 9  may in installed condition be tilted with respect to the illustrations. For example, a supply apparatus may be installed to a receiving station in a tilted condition whereby the main liquid flow direction DL is tilted with respect to, and/or rotated around, a horizontal or vertical, and the respective dimensions D 1 , d 1 , D 2 , d 2 , D 3 , d 3  are tilted accordingly. In any event, it should again be understood that when referring throughout this disclosure to back, front, top, lateral side, side, bottom, height, width, or length or other aspects relating to dimensions, orientations or directions with respect to a surrounding three-dimensional space, this should not be interpreted as fixing the orientation of components of the supply apparatus, unless in certain examples where this is functionally determined. Rather, certain aspects related to orientations are described for the purpose of illustration and clarity. 
       FIG. 48  illustrates a diagrammatic front view (left) and side view (right) of a different example of an interface structure  605 A for a supply container, for example having similar dimensions d 1 , d 2 , d 3  as the example low-profile interface structure described with reference to  FIGS. 8 and 9 . The interface structure  605 A of  FIG. 48  includes a liquid interface  615 A with recesses  671 A at both lateral sides, one of which housing an integrated circuit  674 , and an interface front including an interface front edge  654 Ab. The interface front push edge  654 Ab which functions as both the interface front push area and front edge, sufficient to push against the protective structure of the needle. The recesses  671 A may be at least partially open at the lateral sides  639 A, forming a lateral opening that may also define the lateral guide features  638 A, for example respective guide slots  642 A. 
     The interface front edge  654 Ab extends opposite to the distal side  637 A, adjacent the liquid interface  615 A, for example to push a protective structure for releasing a fluid needle. The interface front edge  654 Ab extends adjacent the container side from which the interface structure  605 A projects when assembled to the container. Integrated circuit contact pads  675 A are provided on the inside of the wall that defines the distal side  637 A of the liquid interface  615 A, laterally next to the liquid output interface  615 A. 
     The interface structure  605 A includes lateral and intermediate guide features  638 A,  640 A to engage corresponding guide rails of a receiving station, such as the guide rails associated with the other example guide features  138  and  140 , respectively, in  FIG. 17 . In the present example of  FIG. 48 , lateral longitudinal guide features  638 A are provided at the lateral sides  639 A of the interface structure  605 A, for example in the form of opposite edges  645 A that extend along the second dimension d 2  of the interface structure  605 A, whereby the opposite edges  645 A may be adapted to engage the respective guide rails. Guide slots  642 A are formed by the opposite edges  645 A. The lateral longitudinal guide features  638 A may facilitate guiding of the interface structure  605 A in the direction along the second interface dimension d 2 , while limiting the degree of freedom of movement in directions along the first interface dimension d 1 . An intermediate longitudinal guide feature  640 A is provided at the distal side  637 A of the interface structure  605 A, for example in the form of opposite edges  647 A that extend along the second dimension d 2  of the interface structure  605 A, whereby the opposite edges  647 A may be adapted to engage the corresponding guide rails. The intermediate longitudinal guide feature  640 A may facilitate guiding of the interface structure  605 A in a direction parallel to the second interface dimension d 2 , while limiting the degree of freedom of movement in directions along the third interface dimension d 3 . Intermediate guide slots  644 A may be formed by the opposite edges  647 A. The edges  645 A,  647 A may have a similar function as the earlier mentioned second lateral guide surfaces  145  and second intermediate guide surfaces  147  as explained with reference to  FIGS. 14, 17A and 17B . 
     Furthermore, the through slot  642 A may function as a clearance for a hook (as shown in  FIG. 18 ). A stop surface  663 A may be provided at the front of the slot  642 A, that may be part of a lateral front wall portion  663 AA. In certain examples, one of the intermediate slot  644 A and the lateral slot  642 A are clearance slots to clear the corresponding guide rail. 
       FIG. 49  illustrates a diagram of an example of a supply apparatus  601 B wherein the interface structure  605 B has separately manufactured interface components.  FIG. 49  also illustrates an example interface structure  605 B having reduced guide features  641 B,  643 B. The interface structure  605 B includes a liquid channel interface  615 B, an interface front area and edge  654 Ba,  654 Bb, respectively adjacent the interface  615 B, key components  665 B including respective key pens and an integrated circuit component  675 B including contact pads. For illustrative purposes the components are drawn as separate blocks, corresponding to separate components that need to be assembled together to form the interface structure  605 B. The components could have been separately molded and/or extruded. 
     The interface structure  605 B includes straight, flat lateral guide surfaces  641 B at the lateral sides  639 B and a straight, flat distal guide surface  643 B at the distal side  637 B of the interface structure  605 B. For example, the lateral guide surfaces  641 B extend approximately parallel to the first and second interface dimension d 1 , d 2  and the intermediate guide surface  643 B extends parallel to the second and third interface dimension d 2 , d 3 . In one example, the guide surfaces  641 B,  643 B are adapted to engage the insides of guide rails of  FIG. 17 . The guide surfaces  641 B,  643 B may facilitate sliding the interface structure  605 B in a receiving station in a direction parallel the second dimension D 2 , d 2 , while limiting the freedom of movement in a direction parallel to the third dimension D 3 , d 3 , for example between corresponding opposite lateral guide rails or surfaces of the receiving station, but the guide surfaces of the interface structure still allow for some freedom of movement along the first dimension D 1 , d 1 , for example upwards in the drawing of  FIG. 49 . 
       FIG. 50  illustrates a diagram of another example of a supply apparatus  601 C. Similar to other examples, the interface structure  605 C of the supply apparatus  601 C includes a liquid interface  615 C, an interface front area and edge  654 Ca,  654 Cb, respectively, and integrated circuit contact pads  675 C near the distal side  637 C. In one example an intermediate guide feature  638 C is provided near the distal side  637 C of the interface structure  605 C. The intermediate guide feature  638 C may include at least one surface to engage a corresponding guide rail of a receiving station. Lateral guide features are omitted in this example interface structure  605 C whereby a user may need to manually position the liquid interface  615 C with respect to the fluid needle with no or few guide surfaces, or in the example where there is the intermediate guide feature  638 C, that intermediate guide feature  638 C may provide some guide functionality for positioning. Also, opposite the lateral side walls  651 C of the container  603 C may provide for rough guidance with respect to the receiving station. In the illustrated example a recess  671 C extends along the container bottom side  613 C, and along the needle receiving liquid channel portion of the liquid channel. The integrated circuit and/or integrated circuit contact pads  675 C extend in the recess  671 C, with the contact surfaces being exposed towards the container  603 C. The recess is open to the lateral side opposite to the needle receiving liquid channel portion. 
       FIG. 50A  illustrates a diagram of a further example of a supply apparatus  601 D and its interface structure  605 D whereby the respective recesses  671 D are open to the lateral sides  639 D of the interface structure  605 D. The recesses  671 D are delimited by base walls  669 D, walls of the needle receiving portion of the liquid channel  617 D, the respective container side  613 D, and inner walls  637 D 1  of the distal side  637 D of the interface structure  605 D. The key pens  665 D extend next to and approximately parallel to the liquid channel, from respective base walls  669 D. An intermediate guide feature  640 D, such as a guide slot, may be provided adjacent, and along, the needle receiving portion of the liquid channel of which the output interface  615 D is illustrated. The intermediate guide feature  640 D may be adapted to limit the freedom of movement in opposite directions parallel to the third interface dimension, with respect to counterpart guide surfaces of a receiving station. End edges of the distal side  637 D of the interface structure  605 D may define (i) first lateral guide surfaces  641 D, for example to engage lateral guide surfaces in the receiving station, and/or (ii) second lateral guide surfaces  645 D, for example to engage lateral guide rails of the receiving station, the first lateral guide surfaces  641 D and second lateral guide surfaces  645 D extending along the second interface dimension. 
     In another example the opening at the lateral side  639 D, between the distal side  637 D and the side  613 D of the container  603 D from which the interface structure  605 D projects, may defined a clearance slot  642 D to clear lateral guide rails of a receiving station rather than being guided by the guide rails. Similarly, the distal side  637 D may be provided with an intermediate guide clearance slot instead of an intermediate guide slot  640 D. Because in certain examples some guidance may be obtained through the key pens  665 D, it may not be needed to provide for separate guide features but certain guide rails may need to be cleared to pass into the receiving station. 
       FIG. 50B  illustrates a diagram of another example of a supply apparatus  601 E and its interface structure  605 E. The interface structure  605 E includes key pens  665 E that extend parallel to, and next to, the needle receiving portion of the liquid output channel, of which only the liquid interface  615 E is illustrated. Each key pen  665 E includes a base portion  683 E at the base of the key pen  665 E, to connecting the key pen  665 E to respective base wall  669 E. In this example, the base walls  669 E of the key pen  665 E extends at the side  613 E of the container  603 D from which the interface structure  605 E projects. For example, the interface structure  605 E may have a support wall  637 Ea 1  at a proximal side  637 E 1  proximal to the container side  613 E from which the interface structure  605 E projects, for example approximately parallel to that container side  613 E. The key pen base portions  683 E protrude out of the proximal side  637 E 1 . The key pens  665 E may be curved between the base portions  683 E and the longitudinal key pen portion that extends approximately parallel to the needle insertion direction NI and main liquid flow direction DL of the needle receiving liquid channel portion. The proximal support wall  637 Ea 1  may extend to the lateral sides where end edges of the wall  637 Ea 1  may form lateral guide features  638 E, for example first lateral guide surfaces  641 E to limit a degree of freedom of movement in a direction of the third interface dimension, with respect to guide surfaces of a receiving station  609 E. For example, the interface structure  605 E does not engage protruding guide rails of the receiving station. The interface structure  605 E may further include an integrated circuit and/or integrated circuit contact pads  675 E along a support wall  637 Ea that defines the distal side  637 E, whereby the wall along which the distal side  637 E and integrated circuit contact pads extend may be parallel to the third and second interface dimensions. A recess  671 E is defined by that wall of the distal side  637 E and contact pads  675 , the needle receiving portion of the liquid output channel, and the proximal side  637 E 1  of the interface structure  605 E. One of the key pens  665 E may extend along, or partly inside of, the recess  671 E. 
     In  FIGS. 50A and 50B , the key pens,  665 E may have predetermined cross sections to one of (i) discriminate between receiving stations or (ii) not discriminate between receiving stations, whereby the latter may be a master key pen. Distal actuating surface areas of the key pens  665 D,  665 E may extend approximately up to the front  654 D,  654 E, or further out of the interface structure  605 D,  605 E beyond the front  654 D,  654 E, as explained earlier with other example key pen structures. 
       FIG. 50C  illustrates a diagram of another example supply apparatus  601 F and interface structure  605 F. Here the interface structure  605 F includes at least one first lateral guide surface  641 F at the lateral sides  639 F, with a lateral clearance slot  642 F to clear corresponding lateral guide rails of the receiving station. In the illustrated example two opposite first lateral guide surfaces  641 F are provided at opposite sides of the lateral clearance slot  642 F. Both lateral sides  639 F may be provided with first lateral guide surfaces  641 F and clearance slots  642 F. In a further example a secure feature such as a stop surface  663 F may be provided near a front of the interface structure  605 F, for example bridging the lateral clearance slot  642 F, at one or both lateral sides  639 F. The interface structure  605 F may include at least one first intermediate guide surface  643 F at the distal side  637 F, with an intermediate clearance slot  644 F to clear a corresponding guide rail of the receiving station. In the illustrated example two opposite first intermediate guide surfaces  643 F are provided at opposite sides of the intermediate clearance slot  644 F. The clearance slots  642 F,  644 F may facilitate passing of the interface structure  605 F along guide rails of a receiving station without being guided by the guide rails. In one example the first guide surfaces  641 F,  643 F and/or outer walls of the container  603 F and/or key pens  665 F may provide for sufficient guidance to fluidically connect the liquid interface  615 F to a liquid input of the receiving station. 
     The example interface structures of  FIGS. 48, 49, 50, 50A, 50B and 50C  may project from the container in a similar manner as other example interface structures described in this disclosure, for example projecting from a first container side, near a second container side that is at approximately straight angles with the first container side, and at a distance from an opposite third side of the container that is opposite to and at a distance from the second side, whereby the container may project beyond the liquid interface edge in the projection direction towards the third side. Also a liquid channel reservoir connecting portion may be provided, for example protruding from the interface structure, to connect to the respective reservoir. Similar to other examples of this disclosure, the interface components may have similar positions with respect to each other and/or the center plane CP. 
       FIG. 51  illustrates a diagram of a cross sectional top view of an example of an interface structure  605 G that, similar to the drawing of  FIG. 50 , does not include fixed keys. The interface structure  605 G comprises a liquid channel  617 G, including the liquid channel interface  615 G, and a further reservoir connecting portion  629 G to connect to the container. A separate key pen structure  665 G is provided which would allow an operator to connect the interface structure  605 G with the liquid needle and data connection of the receiving station, while actuating or unlocking certain actuators in the receiving station with the separate key pen structure  665 G. In this example the key pen structure  665 G includes a pair of key pens which may be similar to any of the example pairs of key pens illustrated throughout this disclosure. The pair of key pens may be connected through a single key pen structure  665 G, for example through a grip portion  669 G, to facilitate manual operation of the key pen structure  665 G. 
       FIGS. 52 and 53  illustrate a diagrammatic front and side view, respectively, of an example supply apparatus  701 A having a different example secure feature  757 A than previous examples and a different example interface structure  705 A than previous examples. A single structure  705 A 2  includes an interface structure  705 A and a container support portion  713 A. The single structure  705 A 2  may be a separately manufactured, e.g. molded, structure for later assembly to the rest of the container  703 A. In this example the support portion  713 A provides for some support to a projecting portion  723 A of the container  703 A, the support portion  713 A and the projecting portion  723 A both projecting beyond the liquid interface  715 A of the interface structure  705 A. The interface structure portion  705 A projects from a bottom of the support portion  713 A. The interface structure portion  705 A includes components that interface with the receiving station including the liquid channel interface  715 A, the integrated circuit contact pads, and at least one of guide features, key pens, etc. within its first, second and third dimensions. The first interface dimension d 1 , which determines the profile height of the interface structure  705 A, extends between the bottom of the support portion  713 A and the bottom of the interface structure  705 A. 
     The supply apparatus  701 A includes secure features  757 A that may, at least to some extent, secure the supply apparatus  701 A to walls  707 A of a receiving station. In one example the secure features  757 A include pads or elements to friction fit the supply apparatus to the receiving station, for example of elastomer material. The supply apparatus  701 A may be pressed between walls of the receiving station whereby the elastomer material provides for sufficient friction, in combination with some clamping force between opposite receiving station walls  707 A, to retain the supply apparatus  701 A in seated condition. Other secure features could include latches, hooks, or clips, for example to latch, hook or clip to edges of the receiving station. These other secure features could be provided in, or attached to, any of the supply apparatus components such as the structure  705 A 2  or interface structure  705 A. The example secure features  157  addressed in other parts of this disclosure, including the clearance  159  and stop  163  at the lateral side  139 , may be omitted, and replaced by these other secure features or the friction fit elements, while certain other interface components such as one or more of the liquid interface  715 A, integrated circuit contact pads, key pens, guide features, etc. could be included in the interface structure  705 A. 
       FIGS. 54 and 55  illustrate a diagrammatic side and back view, respectively, of another example supply apparatus  701 B wherein parts of a support structure  735 B extend over the interface structure  705 B. A back wall  125 B and/or side walls  751 B of the support structure  735 B extend along the interface structure  705 B over the projection distance of the interface structure  705 B, that is, along both the first container and interface dimension D 1 , d 1 . Lateral guide features could be provided in the side walls  751 B of the support structure  735 B next to the interface structure  705 B (not shown). The interface structure  705 B may be, to some extent, embedded in the support structure  735 B. 
       FIGS. 56 and 57  illustrate perspective views of another example supply apparatus  701 C in accordance with aspects of this disclosure, in a partially disassembled state and an assembled state, respectively. In the illustrated example the support structure  735 C may be generally sleeve shaped facilitating that the bag reservoir  733 C can slide into the sleeve shaped support structure  735 C. The support structure  735 C may include a sleeve shaped body portion  751 C and a back and front wall  725 C,  731 C, respectively, to close respective ends of the sleeve shaped body portion  751 C. The body portion  751 C may include an opening through which the interface structure  705 C projects, whereby the opening may be provided near the back  725 C and a projecting portion  723 C may extend over most of the length of the body portion  751 C towards the front  731 C. In an example the support structure  735 C include plastics material. The back  725 C and body portion  751 C may be pre-attached or form a single integral body. In one example the interface structure  705 C may be attached to, or an integral part of, the back  725 C and/or the body portion  751 C. The main liquid flow direction DL may extend out of the liquid interface, along the projecting portion  723 C that projects over and beyond the interface structure  705 C. 
       FIGS. 58 and 59  illustrate perspective views of portions of another example supply apparatus  701 D in accordance with different aspects of this disclosure, wherein in both drawings the bag reservoir has been omitted, and in  FIG. 59  the supply apparatus  701 D is illustrated while being inserted into a receiving station  707 D. The support structure  735 D may be a tray, for example a carton tray, to support the bag. The projection distance PP of the support structure  735 C beyond the liquid interface edge  716 D is indicated in  FIG. 58 , illustrating how the container projects parallel to the main liquid flow direction DL beyond the interface liquid interface edge  716 D. The interface structure  705 D projects from the respective side  713 D of the support structure  735 D, in this example a top side, over the extent of the first interface dimension d 1 . The interface structure  705 D includes cylindrical elongate lateral guide features  738 D at the lateral and distal sides of the interface structure  705 D that serve to guide the interface structure  705 D with respect to corresponding guide rails  738 D 1  of the receiving station  707 D along the main liquid flow direction DL, while limiting the degree of freedom in the directions of the first and third interface dimensions, to position the liquid outlet interface  715 D with respect to the liquid input of the receiving station. 
       FIG. 60  illustrates a diagram of an example supply apparatus  801  and interface structure  805  that include a plurality of fluid interfaces. The container  803  may include at least one of a support structure  835  and reservoir  833 . The interface structure  805  may include at least one of key pens  865 , integrated circuit contact pads  875 , guide features, etc. In addition, in one example the interface structure  805  of  FIG. 60  includes two liquid channels  817 A, B to connect the reservoir  833  with two fluid needles of a single receiving station. The liquid channels  817 A,  817 B may include a liquid input and liquid output, or both liquid channels and interfaces  817 A,  817 B,  815 A,  815 B may be bi-directional. The liquid channels  817 A,  817 B comprise respective interfaces  815 A,  815 B to connect to respective liquid interfaces of the receiving station, for example including seals to seal to the needles. This example supply apparatus  801  facilitates mixing or circulation of liquid in the reservoir  833 . Mixing, moving or recirculating liquid in the reservoir  833  can be advantageous for pigment inks or other liquids, for example to prevent settling of particles in a carrier liquid. 
     The different interface components other than the liquid channel components  815 A,  815 B,  817 A,  817 B have similar functions, positions and orientations as in the other examples of this disclosures. The plurality of liquid interfaces  815 A,  815 B and channels  817 A,  817 B can be positioned adjacent each other, or distanced from each other with perhaps other interface components in between. For example, one or both of the interfaces  815 A,  815 B and/or channels  817 A,  817 B could be moved closer to a lateral side  839 , whereby for example certain interface components, such as the integrated circuit or at least one of the key pens, may extend between the different interfaces  815 A,  815 B and/or channels  817 A,  817 B. 
     In other examples the container of this disclosure may comprise a liquid reservoir and a vent and/or pressurizing mechanism connected to the inside of the reservoir. For example, such container may include a relatively rigid or hard-shell liquid reservoir. A secondary fluid interface may be provided similar to  FIG. 60 , wherein the secondary fluid interface may connect to the internal pressurizing mechanism of the container. The pressurizing mechanism may include a bag, expandable chamber, flexible film, balloon, or air blowing connection, or the like, to allow for pressurization of the inside of the reservoir. Such container may be for a relatively small volume supply apparatuses. The interface structure may project from a respective side of the relatively rigid container. 
     It is also noted that, although this disclosure addresses liquid channels and liquid interfaces, the liquid channels and liquid interfaces may serve to transport any fluid, for example liquids comprising gases. 
     In different examples of this disclosure, integrated circuits and respective contact pads are discussed. Such integrated circuit may include a data storage device and certain processor logic. The integrated circuit may function as a micro-controller, for example a secure micro-controller. Data stored on the storage device may include at least one of characteristics of the liquid, data to indicate a remaining liquid volume, a product ID, digital signatures, base keys for calculating session keys for authenticated data communications, color transform data, etc. In addition, dedicated challenge response logic may be provided in the integrated circuitry, in addition to the data storage device and processor logic. The supply apparatus may be authenticated by a printer controller by issuing certain challenges that the integrated circuit needs to respond to. The integrated circuit may be configured to return at least one of a message authentication code, session key, session key identifier and digitally signed data for verification by the printer controller. In certain examples, warranty, operating conditions and/or service conditions for a printer to which the supply apparatus is connected may depend on positive authentication of the integrated circuit by the printer controller. When a positive authentication cannot be established, this may point to the use of unknown or non-authorized supplies which in turn may increase a risk of damage to the printer, or lower quality print output. Where the integrated circuit cannot be positively authenticated, the printer controller may facilitate switching to a safe or default print mode, for example with reduced yet safer printer operating conditions, and/or facilitating modified warranty and/or service conditions. 
     In this disclosure, when referring to a front, back, top, bottom, side, lateral side, height, width and length of a component, this should in principle be interpreted as for illustration only, because components of the supply apparatus may be oriented in any suitable direction in three-dimensional space. For example, a collapsible liquid reservoir may be emptied in any orientation whereby the liquid interface and main liquid flow direction may be correspondingly directed in any direction, like upwards, downwards, sideways, etc., and the reservoir may correspondingly hang, protrude, stand, incline or point in any direction. The supply apparatus and interface structure of this disclosure may facilitate connection to different types of receiving stations or printers in any orientation. 
     While in this disclosure several examples are shown wherein the container and interface structure are, and/or include, separately manufactured components, for example the container including a carton and bag and the interface structure including a molded assembly, in other examples the container and interface structure may be at least partially manufactured (e.g. molded) together, or certain components of the container may be molded together with certain components of the interface structure. 
     The first, second and third dimensions of the interface structure refer to x, y, and z-axes, and extents along which the interface structure extents. As explained and illustrated, certain examples portions of the interface structure may extent outside of the first, second and third interface dimensions such as the reservoir connecting liquid channel portion or certain protruding support flanges. Hence, the interface dimensions d 1 , d 2 , d 3  may refer to a projecting portion of the interface structure within which some or all of the interface components to interface with the receiving station extend. For example, the front push area edge and the distal side that supports the integrated circuit may extend within and/or define the first interface dimension d 1 . For example, the external lateral sides of the interface structure may define the third interface dimension, and in absence of these lateral sides, at least the opposite key pens may extent within the third interface dimension d 3 . The front liquid interface edge and the back of the interface structure may define the second interface dimension d 2 . 
     In this disclosure reference is made to axes and directions. Axes refer to a specifically oriented imaginary reference lines in three-dimensional space. A direction refers to a general course or direction. 
     In one example the liquid is to flow, mainly, from the container reservoir to the receiving station and hence in this disclosure respective flow directions portions may be referred to as “upstream” and “downstream” along the main liquid flow direction. However, there may be bi-directional flow in the channel between the container and the liquid interface whereby during periods of time a liquid may flow from the receiving station towards the container. Also, there may be two liquid channels with opposite flow directions at a given point in time. It will be understood that the definition of downstream and upstream refers to the main direction of flow between the container and the receiving station for printing. In examples where there are two fluid needles with each, at a given point in time, an opposite direction of flow for recirculating ink in the container, two similar liquid channels and interfaces may be provided in the supply apparatus. Again, each liquid channel may be adapted to facilitate flow in any direction inside the channel and through the interface. Still, the main flow direction will be determined by the general positive delta of liquid that needs to flow towards the receiving station to supply the liquid for printing. 
     Where a receiving station has two protruding needles to connect to a single supply apparatus for recirculating or mixing liquid in a supply apparatus, one needle of the receiving station may be serve as an input and another needle may serve as an output at a given point in time. Correspondingly, the interface structure may include two liquid interfaces and two liquid channels, one liquid interface serving as an input and another as output, although there may be bi-directional flow through each needle and interface. Any second needle and corresponding second liquid interface may have a similar design and configuration a first needle and liquid interface, as addressed throughout this disclosure, whereby the first and second needle/interface may extend in parallel to facilitate insertion and removal of the supply apparatus with respect to the receiving station. Other interface components like the interface front or front push area may similarly be duplicated or enlarged if two liquid channels and interfaces are used. 
     Similar to a secondary liquid needle, in further examples that are included within this disclosure, there may be further fluid needles to communicate gas with the supply apparatus, for example to communicate gas to a space between the reservoir and the support structure, or to communicate gas with a secondary gas reservoir inside the main liquid reservoir. Such further fluid or gas interface may facilitate pressurizing, service, or other functions. In these examples, a gas interface may be provided next to or between the disclosed interface components. 
     The axis along which the main liquid flow direction extends may be determined by internal walls of the needle receiving liquid channel portion and/or internal seal channel, for example by a central axis of these liquid channel components. It will be understood that liquid may not flow exactly straight nor that internal liquid guiding channel walls have to have perfectly round or straight shapes, whereby in certain instances it may be hard to determine an exact liquid flow axis. The skilled person will understand that the liquid flow direction is intended to reflect a general direction of flow from the supply apparatus to a printer receiving station, for example through the inserted needle along a needle axis. Also, the needle insertion direction may be determined by internal walls of the needle receiving liquid channel portion and/or internal seal channel, for example by a central axis of these liquid channel components, to enable insertion of the needle. The main liquid flow direction is parallel and opposite to the needle insertion direction. 
     In this disclosure certain features are identified as “first”, “second”, “third”, etc. to identify different aspects or features that have a similar name or purpose. For example, this disclosure addresses planes, guide features, recesses, keys, and other feature sets wherein individual features within these sets are identified by such “first”, “second”, etc. It will be understood that this type of identification is meant to distinguish between features that have similar aspects or purposes, but that throughout the claims and description a different numbering may be used for the same features depending on the context. For example, depending on the context, what is a sixth or seventh plane in the description may be referred to as a first or second or intermediate or offset plane in a dependent claim or at another location of the description. 
     Shorter or longer key pen lengths than the lengths indicated in this disclosure may be implemented to facilitate actuation, for example shorter than 10 mm or longer than 23 mm. Also, color-discriminating key pens or non-discriminating master key pens can be used whereby either of those may protrude beyond the liquid interface edge for example further than 5 mm or further than 10 mm beyond the liquid interface edge in the main liquid flow direction. 
     The supply of this disclosure can be inserted in a fully filled state, having a relatively high weight, and thereafter be unmounted in a substantially exhausted state, having a relatively lighter weight, in a relatively user-friendly way. During installation, the key pens may actuate upon a receiving station transmission mechanism which may be calibrated to accommodate the difference in weight between insertion and ejection. For example, a relatively light push may be sufficient to insert a filled, relatively high weight supply apparatus, while after exhaustion the empty, relatively low weight supply apparatus may be prevented from launching with respect to the receiving station. The interface structure may facilitate guided and relatively precise alignment of a filled, relatively high weight supply apparatus to a receiving liquid needle, whereby a relatively low amount of effort and experience is required from the operator. 
     Certain aspects addressed in this disclosure may facilitate the use of materials and components that reduce a potential impact on the environment. Certain aspects addressed in this disclosure facilitate space and foot print efficiency of the supply apparatus and associated printer. For example, the supply apparatus may have a relatively thin aspect ratio. For example, the interface structure may have a relatively low projecting profile height, as defined by its first dimension. 
     Other aspects addressed in this disclosure may facilitate enhanced modularity of the supply apparatus components. For example, the interface structure can be used for a wide range of different supply volumes for different printer platforms. In one example a single container or reservoir may be used for multiple volume supply apparatus through partially filling. For example, a filled on-the-shelf supply apparatus may include a reservoir bag that has a capacity of 1 L or more, whereby the same reservoir bag could be used for different supply apparatus products that contain, for example, 500 ml or 700 ml or 1 L of print liquid. 
     Also, the interface structure can be leveraged for connection to a relatively wide variety of different print system platforms. Whereas prior to the filing date of this disclosure an equivalent variety of print system platforms were associated with a wide range of different supply platforms, for example more than three or four different supply platforms of different designs, now the same variety of print system platforms may use a single interface structure and supply apparatus platform. 
     The supply apparatuses, interface structures and components of this disclosure can be applied to fields other than printing, for example any type of liquid dispense system, and/or liquid circulation circuit. For example, the print liquid supply may contain liquids other than print liquids, for example liquids that are to be contained in impermeable reservoirs, to retain certain properties over time. The application areas of these other fields may include medical, pharmaceutical or forensic applications, or food or beverage applications, for example. For that purpose, where in the description and claims a print liquid is mentioned, this may be replaced by any fluid or liquid. Also print systems or print platforms may be replaced by any fluid or liquid handling platform. 
     As noted at the beginning of this description, the examples shown in the figures and described above illustrate but do not limit the invention. Other examples that are not illustrated in this disclosure can be derived through either derivation or combination of different disclosed and non-disclosed features. The foregoing description should not be construed to limit the scope of the invention, which is defined in the following claims. 
     In one aspect, this disclosure involves a print liquid supply apparatus, comprising a container to hold print liquid, and an interface structure to fluidically connect the container to a receiving station. The container has a first, second and third dimension that are perpendicular to each other. The interface structure has a first, second and third dimension parallel to said first, second and third dimension of the container, respectively. In one example, the interface structure projecting outwards with respect to the container along the first dimension of the interface structure. The first dimension of the interface structure may be less than half of the first dimension of the container. The interface structure comprises a liquid interface to fluidically connect to a corresponding fluidic interface of the receiving station, and a liquid channel fluidically connecting the container and the liquid interface, wherein the liquid channel and interface may define a main liquid flow direction approximately parallel to the second dimension of the interface and container. 
     In another aspect, this disclosure involves a print liquid supply apparatus to supply liquid to a liquid needle of a receiving station comprising a liquid container including an at least partially collapsible liquid reservoir to hold at least 90 ml of print liquid, including reservoir wall material adapted to inhibit fluid transfer, and an interface structure at a side of the container. The interface structure includes (i) a rigid molded fluidic structure adapted to facilitate a fluidic connection with the receiving station, (ii) a liquid channel that includes a reservoir connecting portion that fluidically connects to the reservoir to allow the liquid to flow from the reservoir to and through a liquid channel of the interface structure, (iii) a liquid interface of the liquid channel at a distance from the reservoir connecting portion, the interface including a seal to receive a liquid needle, wherein a respective needle receiving liquid channel portion and/or the seal define a needle insertion direction, (iv) a front wall or edge including a push area which is disposed between the liquid interface and the container, (v) at least one key pen base and key pen protruding from the base in a direction parallel and opposite to the needle insertion direction, at a lateral side of the needle receiving liquid channel portion, the key pen having a respective actuating surface area at least 10 mm distant from the base, to pass through a key slot and actuate upon an actuator of the receiving station, wherein the level of the actuating surface area, as measured along the needle insertion direction, is (a) between approximately 5 and 0 mm short of the level of the liquid interface edge and/or front push area, or (b) extends beyond that level; and (vi) a contact pad array at a lateral side of the needle receiving liquid channel portion, wherein the contact pad array is arranged at an opposite to the container, wherein contact surfaces of the contact pads face towards the container, and wherein the key pen, needle receiving liquid channel portion and liquid interface are intersected by a first virtual reference plane parallel to, and at a distance from, a second virtual reference plane that intersects the contact pad array. 
     In again another aspect, this disclosure involves a method of assembling different components to obtain an interface structure and/or supply apparatus of any example of this disclosure, wherein at least one of the to-be-assembled components is collected after a previous usage in a printer in the field. For example, a supply apparatus can be collected after exhaustion, after which the interface structure can be separated from the container. The key pens and the single molded base structure can be disassembled. Then, one of (i) newly manufactured key pens, or (ii) previously used and collected key pens may be connected and positioned with respect to the base structure in an orientation that corresponds to the desired receiving station and liquid type. 
     In other aspects, this disclosure involves an interface structure for any of these liquid supply apparatuses. In another aspect this disclosure involves a key pen. In again others aspect, this disclosure involves an intermediate product to provide any of such liquid supply apparatus wherein the intermediate product may be a kit of components.