Patent Publication Number: US-7721644-B2

Title: Food package holder

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This U.S. patent application is a division of prior U.S. patent application Ser. No. 10/631,492, filed Jul. 30, 2003 now U.S. Pat. No. 7,104,186. 
    
    
     FIELD OF THE INVENTION 
     The invention relates generally to food package holders for retaining a package in a predetermined position between a pair of trays, and more particularly to maintaining the position of the package when the package is inside the drum of an agitating retort during the agitation process. 
     BACKGROUND OF THE INVENTION 
     Recently, a new type of retortable packaging suitable for in-container sterilization of foodstuffs was introduced. Referring to  FIG. 1 , a cross-section of this new packaging material  10  may be seen. The packaging material  10  is a generally flat sheet material that may include at least three layers, a core layer  14  generally composed of cardboard, and two outer layers  12  and  16  each composed of a polymer material. Additionally, packaging material  10  may include a gas barrier layer  18  that may be sealed or laminated to the core layer  14  by a layer of sealing agent  20 . In one embodiment, a layer of binder or adhesive  22  may be used to bond the outer layer  16  to the gas barrier  18 . In some embodiments, the outer layers  12  and  16  are formed from liquid-tight polymer coatings. Ink or printing  24  may be applied to the outside of the outer layers  16  or  12 . Optionally, an additional protective layer (not shown) may be applied over the printing  24  to protect it. Packaging material  10  may include packaging materials generally similar to those disclosed in the following published PCT applications filed by TETRA LAVAL HOLDINGS &amp; FINANCE S A, the disclosures of which are incorporated herein by reference: WO 97/02140 (PACKAGING LAMINATES BASED ON CARDBOARD AND PAPER); WO 02/22462 (A PACKAGING LAMINATE FOR A RETORTABLE PACKAGING CARTON); and WO 02/28637 (A PACKAGING LAMINATE FOR A RETORTABLE PACKAGING CONTAINER). 
     Packaging material  10  may be formed into packages by folding or creasing it into a desired shape. A sealing process may then be used to seal the edges or flaps together. In this manner, containers and/or packages may be formed in a variety of shapes and sizes. 
     As mentioned above, one of the exterior layers  12  or  16  of packaging material  10  may be suitable for printing  24 . Information printed on packaging material  10  may include product related text such as the contents of the package, the brand name of the manufacturer, nutritional information, and/or instructions for use. Printed information may also include aesthetic and trade dress designs. 
     Packages formed from packaging material  10  may be considered “fragile” relative to packages formed from other materials such as metal or glass. Consequently, when handling, including clamping, and processing “fragile” packages constructed from packaging material  10  the strength and rigidity limitations of these packages must be taken into consideration. Generally, packages formed from packaging material  10  have a degree of rigidity that is satisfactory for some types of handling and transportation at ambient temperatures. However, in the case of in-package sterilization, the package may be exposed to temperatures of about 110-130° Celsius (240-266° F.). At sterilization temperatures, the mechanical characteristics of a package formed from packaging material  10  or similar packaging materials may change. Specifically, the package may experience decreased strength and/or increased pliability making handling the packages more difficult. Damage to a package may include dents, abrasion, deformation of the package, or any other undesirable change in the appearance of the package. 
     If the packages are exposed to water or steam during processing, the cut edges of the packaging material  10  may absorb moisture. Specifically, the porous fiber layer of the inner core layer  14  may be prone to absorbing moisture. The absorption of moisture by packaging material  10  may cause the layers to delaminate or become separated. Further, the packaging material may lose a degree of rigidity and strength if too much moisture is absorbed along its cut edges. 
     Because some products must be agitated in-package during processing, commercial retort apparatuses have been developed for this purpose. During agitation, packages must be held firmly to avoid scuffing and/or scratching of the printed information. However, the packages should not be held so firmly that they are damaged by the holding mechanism. Packages that have undergone sterilization or will undergo sterilization in conjunction with agitation may be more difficult to handle because their mechanical characteristics may become altered by the heat of the sterilization process. 
     Because containers formed from packaging material  10  and other packaging materials with similar properties may be unable to withstand the normal clamping load of stacking the packages atop one another to form a complete stack in an agitating retort, the packages may be arranged on independent trays. The independent trays are then arranged vertically on a carrier pallet. After the carrier pallet, including a stack of trays with packages placed between each adjacent pair of trays, is positioned within the retort drum, an upper clamping plate is lowered and clamped atop the stack. The carrier pallet may then be raised to clamp the stack firmly against the upper clamping plate. The trays may include upwardly extending side slats so that when the trays are stacked, the upwardly extending slats of the lower tray engage the upper tray. Between the upper and lower tray a volume is created into which the packages may be positioned. In this manner, the trays absorb the clamping load. Trays for use inside the drum of an agitating retort are well known in the art and do not require a detailed description. 
     While the trays may absorb a portion of the clamping load, the individual packages placed between the trays may move or shift relative to the trays during agitation within the drum of an agitating retort. Moving or shifting may result in damage to the packages including scuffing and scratching of the outer surface of the packages. Additionally, if the shifting of the packages is large enough, they may contact one another. If during rotation, the trays are angled causing the packages to shift toward one edge of the trays, the packages may bear against one another. If a sufficient amount of force is exerted on a particular package, it may become damaged or collapse. Particularly, if trays are rotated approximately 90° from horizontal, the packages may shift toward the lower edge of the tray and stack vertically upon one another. In this manner, the packages on the bottom of the stack may be exposed to the most force from the other packages in the stack making the bottom packages vulnerable to damage. Further, if shifting causes the packages to clump together, poor heat transfer to each package within the clump may result during sterilization. Therefore, a need exists for a package holder that is capable of retaining packages in a desired position during agitation in an agitating retort without damaging the packages. Particularly, a need exists for an apparatus capable of holding packages made from the new packaging material  10  and packaging materials with similar mechanical characteristics during processing (such as agitation within an agitating retort) and handling. 
     In addition to dimensional variation among the packages themselves, the trays may also contain variations in shape and size. Particularly, the trays may include manufacturing inaccuracies or other distortions due to repetitive use and/or handling. Some of this variation may result in trays of varying sizes or trays with an irregular package receiving surface. The package receiving surface is the portion of the tray that will receive at least one package for processing such as agitation and/or sterilization. Therefore, a need exists for a means of holding the packages in a desired position that is capable of coping with both the variation in the package dimension and the variation present in the trays. Similarly, a need exists for a device that provides a large deflection capability with minimal change in force applied to the package. 
     SUMMARY OF THE INVENTION 
     An apparatus is provided for substantially maintaining the position of a plurality of packages between a pair of trays inside the drum of an agitating retort when the agitation process is applied to the packages. The apparatus includes a first positioning means disposed on one of the trays for holding the packages in a desired position. In one embodiment, the first positioning means may include a spring or resilient member. In another embodiment, the first positioning means may include a bellows member. In yet another embodiment, the first positioning means may include corrugated or contoured pad. Additionally, the first positioning means may include a linear positioning member that is placed between two neighboring packages. The linear positioning member may include longitudinal chambers that are at least partially collapsible when force is applied to the linear positioning member. The linear positioning member may also include a lip or divider that may extend between two neighboring packages to assist in retaining the packages in a desired location and aid in preventing contact between the packages. Further, the divider projection may offer some support to the faces of the package. Supporting the faces of the package may limit the flexing or deflection of the package faces due to the shifting of the contents of the package during agitation. 
     When the trays are stacked, a volume is formed between the trays into which the packages may be positioned. The packages may be located between the first positioning means and one of the trays. In this manner, the first positioning means substantially retains the packages in a predetermined position relative to the pair of trays. 
     In alternate embodiments, the first positioning means includes a rigid pad that is disposed between the package and the tray. At least one resilient member may be disposed between the rigid pad and the tray. In some embodiments, an optional resilient member is located on the opposite side of the rigid pad from the first resilient member. 
     In some embodiments, the apparatus includes a second positioning means disposed between the other tray and the packages. The second positioning means may include any of the structures included in the first positioning means. In another embodiment, the second positioning means may include a flexible pad. In yet another embodiment, the flexible pad may include divider projections that assist in retaining the packages in a desired position. In this manner, the packages are substantially retained in a predetermined position relative to the pair of trays by the first and second positioning means. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing aspects and many of the attendant advantages of this invention will become more readily appreciated as the same become better understood by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein: 
         FIG. 1  is an illustration of a retortable packaging material substantially composed of paperboard; 
         FIGS. 2A-B  are non-limiting illustrations of one embodiment of a package configuration constructed from the material depicted in  FIG. 1 ; 
         FIGS. 3A-F  are illustrations of various unique orientations of the package of  FIGS. 2A-B  on a surface; 
         FIG. 4A  depicts a front cross-sectional view of the inside of an agitating retort drum known in the art; 
         FIG. 4B  depicts a top cross-sectional view of a stack of trays inside the agitating retort drum depicted in  FIG. 4A ; 
         FIG. 5  depicts an embodiment of a package holder constructed in accordance with the present invention; 
         FIG. 6  depicts an embodiment of a package holder constructed in accordance with the present invention; 
         FIG. 7  depicts an embodiment of a package holder constructed in accordance with the present invention; 
         FIG. 8A  depicts an embodiment of a package holder constructed in accordance with the present invention; 
         FIG. 8B  depicts an alternate embodiment of a package holder depicted in  FIG. 8A  constructed in accordance with the present invention; 
         FIG. 9  depicts an embodiment of a package holder constructed in accordance with the present invention; 
         FIG. 10  depicts an embodiment of a package holder constructed in accordance with the present invention; 
         FIG. 11  depicts an embodiment of a package holder constructed in accordance with the present invention; 
         FIG. 12  depicts an embodiment of a package holder constructed in accordance with the present invention; 
         FIGS. 13A-B  depict an embodiment of a package holder constructed in accordance with the present invention; 
         FIG. 14  depicts a cross-sectional view of an embodiment of a linear positioning member of the package holder depicted in  FIGS. 13A-B ; 
         FIG. 15  depicts a cross-sectional view of an embodiment of a flexible pad of a package holder constructed in accordance with the present invention; 
         FIG. 16A  depicts a front cross-sectional view of a stack of trays incorporating the package holder depicted in  FIGS. 13A-B  inside an agitating retort drum known in the art; 
       FIG.  16 B 1  depicts a top view of an embodiment of a carrier pallet suitable to stack trays upon and be received inside an agitating retort drum depicted in  FIG. 16A ; 
       FIG.  16 B 2  depicts a front view of the carrier pallet depicted in FIG.  16 B 1 ; 
       FIG.  16 B 3  depicts a side view of the carrier pallet depicted in FIGS.  16 B 1  and  16 B 2 ; 
       FIG.  16 C 1  depicts a top view of an embodiment of a tray suitable to be stacked on the carrier pallet of FIGS.  16 B 1 - 16 B 3  and received inside the agitating retort drum depicted in  FIG. 16A ; 
       FIG.  16 C 2  is a side elevational view of FIG.  16 C 1 ; 
       FIG.  16 C 3  is a cross-sectional view of FIG.  16 C 2  taken substantially along lines  16 C 3 - 16 C 3  thereof; 
       FIG.  16 D 1  depicts a top view of another embodiment of a tray suitable to be stacked on the carrier pallet of FIGS.  16 B 1 - 16 B 3 , and received inside the agitating retort drum depicted in  FIG. 16A ; 
       FIG.  16 D 2  is an elevational view of FIG.  16 D 1 ; 
       FIG.  16 D 3  is a cross-sectional view of FIG.  16 D 1  taken substantially along lines  16 D 3 - 16 D 3  thereof; 
       FIG.  16 E 1  is a top view of an embodiment of a top tray suitable to be stacked on trays  16 C 1 ,  16 D 1  or trays of similar construction; 
       FIG.  16 E 2  is a side elevational view of FIG.  16 E 1 ; 
       FIG.  16 E 3  is a cross-sectional view of FIG.  16 E 1  taken substantially along lines  16 E 3 - 16 E 3  thereof; 
         FIG. 17  depicts a cross-sectional view of an embodiment of a linear positioning member of a package holder constructed in accordance with the present invention; 
         FIG. 18  depicts a cross-sectional view of an embodiment of a linear positioning member of a package holder constructed in accordance with the present invention; 
         FIGS. 19A-C  depict cross-sectional views of embodiments of linear positioning members of a package holder constructed in accordance with the present invention; 
         FIG. 20  depicts another cross-section view of an embodiment of a linear positioning member of a package holder constructed in accordance with the present invention; 
         FIG. 21  depicts a cross-sectional view of an embodiment of a linear positioning member of a package holder constructed in accordance with the present invention; 
         FIG. 22  depicts a cross-sectional view of an embodiment of a linear positioning member of a package holder constructed in accordance with the present invention; 
         FIG. 23  depicts a cross-sectional view of an embodiment of a linear positioning member of a package holder constructed in accordance with the present invention; 
         FIG. 24  is cross-sectional view of a further embodiment of a linear positioning member of a package holder constructed in accordance with the present invention; 
         FIG. 25  is a cross-sectional view of an embodiment of a further linear positioning member of a package holder constructed in accordance with the present invention; 
         FIG. 26  is a cross-sectional view of a further embodiment of a linear positioning member of a package holder constructed in accordance with the present invention; 
         FIG. 26A  is a cross-sectional view of a further embodiment of a linear positioning member constructed in accordance with the present invention; 
         FIG. 26B  is a cross-sectional view of a further embodiment of a linear positioning member constructed in accordance with the present invention. 
         FIG. 26C  is a cross-sectional view of a further embodiment of a linear positioning member constructed in accordance with the present invention; 
         FIG. 27  is a fragmentary elevational view of a tray constructed in accordance with the present invention utilizing the linear positioning member of  FIG. 25 ; 
         FIG. 27A  is a top view of the tray corresponding to  FIGS. 25 and 27 ; 
         FIG. 27B  is an elevational view of the tray of  FIG. 27A ; 
         FIG. 27C  is a cross-sectional view of  FIG. 27A , taken substantially along lines  27 C- 27 C thereof; 
         FIGS. 28 and 29  depict a further embodiment of a linear positioning member and tray construction in accordance with the present invention; 
         FIG. 30  is a partial plan view of a portion of a tray and linear positioning member of a further embodiment of the present invention; 
         FIG. 31  is a fragmentary elevational view of  FIG. 30 ; 
         FIG. 32  is a fragmentary elevational view of a further tray and holder constructed in accordance with the present invention; 
         FIG. 33  is a fragmentary view taken from the side of  FIG. 32 ; 
         FIG. 34  is a cross-sectional fragmentary view of a further embodiment of the present invention. 
         FIG. 35  is a cross-sectional view of a further embodiment of a linear positioning member constructed in accordance with the present invention; 
         FIG. 36  is a side elevational view of a tray constructed in accordance with the present invention utilizing the linear positioning member of  FIG. 35 ; and 
         FIG. 37  is a cross-sectional view of  FIG. 36  taken substantially along the lines  37 - 37  thereof. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The present invention provides a package holder or package clamping mechanism for retaining the position of a plurality of packages between a pair of trays inside the drum of an agitating retort. Using the present invention, the packages are generally retained in their desired position when the agitation process is applied to the plurality of packages. 
     Referring to  FIGS. 2A and 2B , an exemplary package  30  formed from packaging material  10  may be viewed. While packaging material  10  is discussed in detail herein, it is generally understood by those of ordinary skill in the art that packaging materials with properties similar to those of packaging material  10  may include similar mechanical characteristics. Therefore, packages made from other packaging materials that require similar clamping loads but have limited strength and rigidity, particularly at sterilization temperatures, may utilized the present invention. In other words, packages made from materials other than packaging material  10  may be considered “fragile” and may utilize the present invention. Further, any package including printing along its outer surface may utilize the present invention to avoid scratching or scuffing the outer surface of the package. These packages may be constructed from stronger, more resilient materials such as glass and metal. Particularly, the processing of lithographed drink cans may benefit from the present invention. 
     Because package  30  may be formed by folding, the dimensions of each package  30  may vary by more than 1 mm. The presence of flaps  34  may also cause the outer dimensions of the package  30  to vary. While packages of various sizes and shapes may be produced from packaging material  10  and similar packaging materials with comparable strength and heat resistant properties, package  30  is provided for illustrative purposes. Those of ordinary skill in the art will appreciate that alternate package shapes may also be appropriate for use with the present invention. Exemplary package  30  includes an outer surface  36  upon which printed information  38  is provided. While printed information  38  is depicted on the front  48  in  FIG. 2A , it is apparent to those of ordinary skill in the art that printing  38  may appear along any face of package  30 . The package  30  may be generally rectilinear in shape and may have a top  40 , bottom  42 , right side  44 , left side  46 , front  48  and back  50 . Alternatively, package  30  may have a generally cylindrical or prismatic shape with substantially flat faces at opposite ends of the package. Regardless of the shape of package  30 , any of the faces of package  30  may include printing. Generally speaking, the contents of package  30  may include foodstuffs that require both sterilization and agitation such as many types of liquid to semi-liquid foodstuffs including many types of ready-meals and pet food. 
     Referring to  FIGS. 3A-3F , the various orientations of the package upon a tray may be viewed. Generally speaking, the particular orientation of the package  30  chosen does not matter. However, the number of packages that may be placed between a pair of trays and the number of package clamping apparatuses required to hold the packages may vary with the orientation of the packages between the trays. Further, the effects of the shifting of the contents in the package during agitation may vary depending upon the orientation chosen. 
     Referring to  FIGS. 4A and 4B , packages  30  arranged on trays  70  within a typical retort drum  60  may be viewed. While retort drum  60  is described in some detail, retort drum  60  is provided to illustrate a non-limiting example of a typical retort drum. It is apparent to those of ordinary skill in the art that alternate embodiments of agitating retorts and retort drums may incorporate the present invention and are therefore within the scope of the present invention.  FIG. 4A  depicts a cross-sectional view from the front of the retort drum  60 . 
     As discussed in the Background, the trays  70  are stacked on carrier pallet  64 . Then, the carrier pallet  64  is moved on wheels  68  by a central drive chain  69  until the stack is in the desired location within the retort drum  60 . Next, a clamping plate  72  is lowered until it rests on top of the stack and mechanically locks itself. Then, the carrier pallet  64  is lifted by the lift cylinders  76  and the stack is compressed against the locked clamping plate  72 . At this point, the stack is suitably clamped to initiate the agitation process. 
     Region  74  illustrates packages  30  arranged in the general orientation depicted in  FIG. 3A  between trays  70 . Region  78  depicts packages  30  arranged in the general orientation depicted in  FIG. 3C  between trays  70 . As can be seen in  FIG. 4A , it may be desirable to arrange the packages in the same orientation between a particular pair of trays  70 . However, this is not necessarily required. The retort drum  60  rotates the packages  30  about center point  62  in the direction of arrow  66 . As the retort drum  60  rotates, the contents of packages  30  are agitated. 
     Referring to  FIG. 4B , a cross-sectional view is shown of the stack inside retort drum  60 . Both the clamping plate  72  and the top tray have been removed so that a tray shown supporting a plurality of packages  30  may be viewed. Packages  30  in this view are depicted positioned on tray  70 . As can be seen in  FIG. 4B , it may be desirable to arrange packages  30  into horizontal rows across the package receiving surfaces of trays  70 . Further, it may be beneficial to arrange the packages  30  within the parallel rows so that the packages form a second set of parallel rows that are orthogonal to the first set of parallel rows. In this manner, the packages are arranged in a two-dimensional grid-like pattern. The retort drum  60  rotates about axis  62  in the general direction of arrow  66 . However, it is apparent to one of ordinary skill in the art that the drum may rotate about axis  62  in the opposite direction to that indicated by arrow  66 . 
     While rotational retort apparatuses have been discussed above, it is apparent to those of ordinary skill in the art that additional agitation processes may also utilize the present invention. These agitation processes may include apparatuses that shake and/or rock the packages  30 , as well as apparatuses that combine shaking and/or rocking with rotational agitation. 
     During agitation, the packages  30  positioned between trays  70  may shift in position. As discussed above, this shifting may result in damage to the packages  30  and/or the printing  38  on the packages  30 . Therefore, it is desirable to use a package holding mechanism to retain the packages substantially stationary in a desired position. 
     Referring to  FIG. 5 , a first embodiment of an apparatus  100  for substantially retaining the packages in a desired positions is provided. Package  30  is positioned between upper tray  102  and lower tray  104 . A first positioning assembly  106  is disposed between upper tray  102  and package  30 . Optionally, a second positioning assembly  108  may be disposed between lower tray  104  and package  30 . First positioning assembly  106  may include at least one resilient member or compression spring  112  disposed between upper tray  102  and one or more faces of each package  30 . In one embodiment, spring  112  may be coupled to the surface of tray  102  in any manner known in the art including adhesives, screws, rivets, bolts, and clips. 
     Spring  112  may exert force on a portion of a face of package  30  biasing package  30  against lower tray  104 . In this manner, the force exerted by spring  112  resists movement of package  30  during agitation. While the springs  112  depicted in  FIG. 5  are positioned approximately near the center of one of the faces of package  30 , it is apparent to those of ordinary skill in the art that the spring  112  may be positioned closer to the edge of the face in any direction. Further, additional springs may be disposed between upper tray  102  and one or more faces of package  30 . 
     Spring  112  may be any suitable spring known in the art such as coil springs. Spring  112  may be formed from any suitable material known in the spring mechanism art including metals, such as steel and copper, and plastics and rubber or other type of elastomer. Spring  112  may have a generally circular or ovoid cross-sectional shape or other suitable cross-sectional shape. The size of spring  112  may be determined based upon the size and weight of packages  30  and their contents. 
     The second positioning assembly  108  may include one or more springs placed between package  30  and lower tray  104 . In another embodiment, the second positioning assembly  108  may include a flexible pad  114 . Flexible pad  114  may exert an opposing force to the force of spring  112 . In this manner, package  30  may be clamped between the first positioning assembly  106  and the second positioning assembly  108 . Flexible pad  114  may yield to the force exerted by spring  112  and receive package  30  into a depression formed by the force of the spring on package  30  that is translated by the package  30  to the flexible pad  114 . In this manner, the edges of the depression may help to maintain the package in the desired position. In some embodiments, the flexible pad may prevent lower tray  104  from scratching or scuffing package  30 . In some embodiments, flexible pad  114  includes perforations therein. Flexible pad  114  may be constructed from a suitable flexible sheet material such as silicone rubber, silicone foam-rubber, EPDM, polypropylene or any elastic material that can withstand a steam, steam-air, or steam-air-water environment at temperatures up to approximately 130° C. The flexible pad  114  of the second positioning mechanism  108  may be coupled to the surface of tray  104  in any manner known in the art including adhesives, screws, rivets, bolts, and clips. Alternately, the flexible pad  114  may be held in position by side slats  116  included on lower tray  104 . 
     Referring to  FIG. 6 , a second embodiment may be viewed. While the package included with this embodiment is depicted in a different orientation from the package depicted in  FIG. 5 , it is apparent to those of ordinary skill in the art that any orientation of the package may be used with any of the embodiments depicted herein. The particular orientation depicted with a particular embodiment is merely illustrative and in no way limiting. The package holder  130 , depicted in  FIG. 6 , is disposed between upper tray  132  and lower tray  134 . The optional second positioning assembly  138  may include a pad  144  similar to pad  114  of the previous embodiment. However, the first positioning mechanism  136  of this embodiment includes a resilient member formed in a flexible shape  142 . In one embodiment, flexible shape  142  may be coupled to the surface of tray  132  in any manner known in the art including adhesives, screws, bolts, rivets, and clips. 
     Flexible shape  142  may include voids into which portions of the flexible shape  142  may be compressed. The flexible shape may be substantially bulbous or hollow so that wall defining the flexible shape  142  may deform when a load is applied. Alternately, flexible shape  142  may be formed from a solid piece of compressible material such as a sponge-like or foam rubber-like material including many small voids. Compression of the flexible shape  142  exerts a force on package  30  that biases the package  30  against the lower tray  134 . While a single flexible shape  142  is positioned between package  30  and upper tray  132  in  FIG. 6 , it is apparent to those of ordinary skill that more than one flexible shape  142  may be disposed between upper tray  132  and package  30 . Further, while flexible shape  142  is depicted as having a generally circular or ovoid cross-sectional shape, it is apparent to those of ordinary skill in the art that many cross-sectional shapes may be used including square, rectangular, octagonal, triangular, or arbitrary. Preferably, flexible shape  142  is formed from semi-rigid flexible material such as silicone rubber, EPDM, polypropylene, or any elastic material (for example, perfluorinated elastomers or fluorinated copolymers) that can withstand a steam, steam-air, or steam-air-water environment at temperatures up to approximately 130° C. 
     Flexible shape  142  may be of a sufficient length to extend across more than one row of packages  30 . In this manner, a single flexible shape  142  may hold more than one package in a desired position. In one embodiment, the flexible shape is a generally annular member that may be generally rectilinear or cylindrical in shape. The length of the flexible shape  142  may be determined by the number of rows spanned or the size of the drum of the agitating retort. The size of flexible shape  142  may be determined based on the size and weight of the packages  30  and their contents. 
     Referring to  FIG. 7 , a third embodiment of the present invention is depicted. Package holding or retaining mechanism  160  includes an optional second positioning mechanism  168  and a first positioning mechanism  166  disposed between upper tray  162  and lower tray  164 . Optional second positioning mechanism  168  may be similar to the second positioning mechanism  108  depicted in  FIG. 5  and may include a flexible pad  174 . First positioning mechanism  166  may include a compressible bellows member  172 . Bellows member  172  is disposed between upper tray  162  and package  30 . Bellows member  172  may include any bellows known in the art including plastic or metal formed into an accordion-type compressible bellows. In one embodiment, bellows member  172  may be coupled to the surface of the upper tray  162  in any manner known in the art including adhesives, screws, bolts, rivets, and clips. In a manner similar to the flexible shape  142  (shown in  FIG. 6 ), the bellows member  172  may extend beyond one row of packages to hold packages in other rows. Likewise, the bellows member  172  may be of approximately the same size as the flexible member  142 . 
     Bellows member  172  exerts force on package  30  that biases it against the lower tray  164 , clamping package  30  between upper tray  162  and lower tray. Bellows member  172  also resists the movement of package  30  during the agitation process. If bellows member  172  extends beyond the edge of the face of package  30 , forces exerted upon the bellows member may cause it to compress forming a depression in the bellows member. The edges of the depression formed in the bellows member  172  may help retain the package  30  in its desired position. 
     Alternatively, bellows member  172  may be an inflatable member including any inflatable bag or inflatable bellows known in the art. In one embodiment, the inflatable member may include a valve, not shown, that may be used to communicate with the interior of the inflatable member. Such a value may allow the inflatable member to be inflated and deflated. In this manner, the level of inflation of the inflatable member could be adjusted based on the rotational position of the packages. Such an adjustment could be effected automatically by the retort apparatus. 
     Referring to  FIG. 8A , a fourth embodiment of the present invention is depicted. Package holding apparatus  180  includes an optional second positioning mechanism  188  in the form of pad  194  disposed on the lower tray  184  similar to the optional second positioning mechanism  108  depicted in  FIG. 5 . The first positioning mechanism  186  generally includes a pad  192  bearing against package  30  and at least one spring or resilient member  190  disposed between the upper tray  182  and pad  192 . Resilient member  190  may be generally similar to spring  112  of  FIG. 5 . Pad  192  may be generally similar to pad  114  of  FIG. 5 . Alternatively, pad  192  may be rigid. In an embodiment with a rigid pad  192 , the pad may be constructed from metal, hard plastic, or other suitable rigid materials. The package  30  is retained in a desired position by resilient member  190  exerting a force against pad  192  that is translated generally evenly against the adjacent face of package  30  biasing the package against either of the pad  194  or the lower tray  184 . Like the embodiment depicted in  FIG. 5 , at least one resilient member  190  may be coupled to the surface of the upper tray  182  in any manner suitable for coupling spring  112  to upper tray  102 . 
     This arrangement of the resilient members  190  and pad  192  allows the first positioning mechanism  186  to be constructed as a subassembly without regard to the position of individual packages. Because the resilient members  190  do not contact the packages  30  directly, the resilient members  190  need not be located adjacent to the packages. Instead, resilient members may be located anywhere between the upper tray  182  and the pad  192 . Pad  192  will transfer the biasing forces of the resilient members  190  to the packages  30 . While  FIG. 8A  depicts resilient members  190  as springs, it is apparent to those of ordinary skill in the art that other types of resilient members such as flexible shapes, bellows members, and inflatable members may be used. 
       FIG. 8B  depicts an alternate embodiment of the first positioning mechanism  186 . First positioning mechanism  186 ′ includes downwardly projecting divider projections  196  formed in pad  192 ′. These divider projections  196  may be useful to prevent shifting of the packages  30 . Further divider projections  196  may prevent the packages from contacting one another during processing. Divider projections  196  may be 2-10 mm and preferably about 5 mm high, 2-10 mm and preferably about 5 mm wide, and 2-10 mm and preferably about 5 mm long. Divider projections  196  may be tapered along their height so that the distal portion has a smaller cross-sectional area than the proximal portion to facilitate loading packages between the divider projections  196 . 
     Referring to  FIG. 9 , a fifth embodiment of the present invention is depicted. Retaining apparatus  200  includes a first positioning mechanism  206  and an optional second positioning assembly  208  similar to that depicted in  FIG. 5 . In this regard, the second positioning assembly  208  may include a pad  214 . First positioning mechanism  206  may include a flexible corrugated pad  212 . Because corrugation is a relatively high frequency wave-like pattern formed in a sheet-like material, it is appreciated by those of ordinary skill that any relatively high-frequency pattern formed in a flexible sheet material may be used. The amplitude of the wave-like pattern and its frequency may be determined from or based on the size and weight of packages  30 . Corrugated pad  212  may be coupled to the surface of the upper tray  202  in any manner known in the art including, for example, adhesives, screws, bolts, rivets, and clips. Alternatively, the thickness of the corrugated pad  212  may be suitably sized so that corrugated pad  212  bears against both the upper tray and at least one face of the packages  30 . In this manner, the corrugated pad  212  may be held in place. 
     In one embodiment, natural or synthetic rubber may be used to form corrugated pad  212 . However, other suitable materials may be used including silicone rubber, EPDM, polypropylene, or any elastic material (for example, perfluorinated elastomer or fluorinated copolymers) that can withstand a steam, steam-air, or steam-air-water environment at temperatures up to approximately 130° C. Corrugated pad  212  resists compression between package  30  and upper tray  202 . In this manner, movement of package  30  is resisted by corrugated pad  212 . 
     Referring to  FIG. 10 , a sixth embodiment of a package holding apparatus constructed in accordance with the present invention is depicted. Package holder  220  includes a first positioning mechanism  226  and an optional second positioning assembly  228  that both include a contoured pad ( 230  and  232 , respectively). Contoured pad  230  may be coupled to the surface of the upper tray  222  in any manner known in the art including adhesives, screws, bolts, rivets, and clips. In a like manner, contoured pad  232  may be coupled to the surface of the lower tray  224 . Alternatively, contoured pad  232  may be held in place by either the force of the packages bearing against the contoured pad  232  or side slats  238  included on the lower tray  224 . 
     Contoured pads  230  and  232  generally include divider projections  234  that may be positioned to extend between packages  30  to retain the packages  30  in a desired position. Projections  234  may be located at one or more corners of package  30 . Further, projections  234  may traverse a portion of one or more faces of the package  30 . Projections  234  may also surround a portion of the package  30  or the entire perimeter of the package  30 . Projections  234  may contact one or more faces of the package  30  or be spaced from the faces of the package  30 . The projections  234  may be suitably sized based upon the size and weight of packages  30 . It may be desirable to angle or taper the sidewalls of projections  234  so that they will guide the packages into a predetermined position during the loading of the trays. Further, if the packages  30  shift, the sloped sidewalls  235  of projections  234  may gently guide the packages  230  back into their desired positions. Between projections  234 , cavities or recesses  236  may be formed. In one embodiment, packages  30  are positioned within recesses  236 . Therefore, the size of package  30  may be used to determine the width and length of recesses  236 . In this embodiment, the contoured pads  230  and  232  may provide a degree of necessary resilience to retain the packages in their positions. Contoured pads  230  and  232  may be constructed from any suitable rigid or semi-rigid material known in the art. Particularly, contoured pads  230  and  232  may be constructed from silicon rubber, silicon foam rubber, polypropylene, and any other elastomer that can withstand the retort environment. 
     Referring to  FIG. 11 , a seventh embodiment of a package holder constructed in accordance with the present invention is depicted. Package holder apparatus  260  may include an optional second positioning assembly  268  similar to that depicted in  FIG. 5 . In this regard the second positioning assembly may include a resilient pad  274 . Package holder  260  includes a first positioning assembly  266  with a contoured pad  272  disposed on the packages  30  similarly to the contoured pad  230  depicted on  FIG. 10 . The first positioning assembly  266  may also include a rigid pad  276  that is disposed on or above contoured pad  272 . Rigid pad  276  may be substantially planar and formed from a rigid metallic, hard plastic, or other type of rigid sheet material. Rigid pad  276  may be large enough to cover the entire contoured pad  272  or a portion thereof. Rigid pad  276  may also be larger than contoured pad  272 . 
     Between rigid pad  276  and upper tray  262 , at least one resilient member  280  may be positioned. Resilient member  280  may resist excessive movement of package  30  toward upper tray  262 . Resilient member  280  may also bias package  30  against either lower tray  264  or flexible pad  274 . Resilient member  280  may be any suitably resilient member known in the art including a spring, similar to spring  112 , flexible shape similar to flexible shape  142 , and/or bellows similar to bellows member  172  above. Resilient member  280  may be coupled to the surface of the upper tray  202  in any manner suitable for coupling resilient member  142  to upper tray  132  (depicted in  FIG. 6 ). 
     Forces exerted by the packages  30  may be translated through contoured pad  272  and deflect a portion of rigid pad  276  spaced from resilient members  280 . The rigidity of rigid pad  276  may resist deflection exerting an opposing force on the package  30 . One or more resilient members  280  may be placed along the periphery of the rigid pad spaced from the edge so that the portion of the rigid pad  276  more toward its center may deflect in response to an applied load. 
     In the embodiment depicted in  FIG. 11 , the trays  262  and  264  include downwardly extending slats  282  and upwardly extending slats  284 . In one embodiment, both the upwardly and downwardly extending slats occur along the same two opposing edges of the tray. In another embodiment, both the upwardly and downwardly extending slats occur along all of the edges of the trays. When the upper and lower trays are stacked, the downward extending slat  282  engages a portion of the upwardly extending slat  284 . In the embodiment depicted in  FIG. 11 , the upwardly extending slat  284  includes a horizontal flange  286 . The downwardly extending slat  282  may bear against the horizontal flange  286  when upper tray  262  is stacked upon lower tray  264 . The lower surface of the upper tray  262 , the inside surface of slat  282 , and the upper surface of horizontal flange  286  define a recess  290 . Recess  290  may include projections or ledges  292  that project from the inside surface of the downwardly extending slat  282 . Rigid pad  276  may be positioned between two ledges  292 . In this manner, the vertical movement of the rigid pad  276  may be limited by the ledges  292 . In some embodiments, the rigid pad  276  may be positioned to bear against the underside of one of the pair the ledges (as shown in  FIG. 11 ). However, it is apparent to those of ordinary skill in the art that the combined thickness of the second positioning mechanism (if present), package  30 , contoured pad  272 , and rigid pad  276  may determine whether the top surface of the rigid pad  276  bears against the underside of one of the ledges  292 . In some embodiments, ledges  292  are substantially rigid and will not appreciably deflect to absorb load. 
     A portion of the upward load exerted by the packages  30  on contoured pad  272  may be transferred to the rigid pad  276 . A portion of this upward load transferred to the rigid pad  276  may then be absorbed by its deflection or upward movement and/or transferred to the resilient member  280 . Resilient member  280  may compress to absorb the load. 
     Referring to  FIG. 12 , an eighth embodiment of a package holding apparatus constructed in accordance with the present invention is depicted. The package holding apparatus  300  is somewhat similar to the embodiment depicted in  FIG. 11  except that recess  330  does not include ledges and a second set of resilient members  336  are positioned between the lower surface of the rigid pad  316  and the lower inside surface of recess  330 . 
     A portion of the upward load exerted by the packages  30  on contoured pad  312  may be transferred to the rigid pad  316 . A portion of the upward load transferred to the rigid pad  316  may then be absorbed by its deflection and/or transferred to the resilient member  320 . Resilient member  320  may compress to absorb the load. In some embodiments, the combined thickness of resilient member  320 , rigid pad  316 , and resilient member  336  approximates the vertical height of the recess so that the resilient member  336  bears against the lower inside surface of the recess  330 . In one embodiment, resilient member  336  is coupled to horizontal flange  342  of slat  344  in any suitable manner. In one embodiment, a resilient member  336  may be positioned directly opposite to a corresponding resilient member  320 . Resilient members  336  oppose the forces of resilient members  320 , and the opposing forces of resilient members  320  and  336  may maintain rigid pad  316  in a substantially fixed position. 
     A ninth embodiment of the present invention is depicted in  FIGS. 13A-13B .  FIG. 13A  depicts a lateral elevational view of a package holder  400  including a first positioning mechanism  406  that includes a linear positioning member  412 .  FIG. 13B  depicts a longitudinal elevational view along a portion of the length of the linear positioning member  412 . Package holder  400  includes an optional second positioning mechanism  408  substantially similar to the second positioning mechanism  108  of package holder  100 . In this regard, positioning mechanism  408  may include a resilient pad  414 . 
     Linear positioning member  412  may have a generally annular or bulbous shape in cross-section. Linear positioning member  412  may be positioned along the lower package receiving surface of upper tray  402  at a location that is between two adjacent packages  30 . The linear positioning member  412  may bear against or abut at least one face of each package. In this manner, linear positioning member  412  is disposed between upper tray  402  and both adjacently positioned packages  30 . 
     Referring to  FIG. 13B , dividers such as projections  416  may be included on flexible pad  414  to assist in maintaining packages  30  in their desired position. The spacing of the divider projections  416  should correspond to the size of the package  30 . Suitable dimensions for divider projections  416  include 2-10 mm and preferably about 5 mm high, 2-10 mm and preferably about 5 mm wide, and extend over the width of the pad  404 . Divider projections  416  may be tapered so that the distal most portion has a smaller cross-sectional area than the proximal most portion to facilitate loading packages between the divider projections. 
     Referring to  FIG. 14 , a detailed cross-sectional view of linear positioning member  412  is provided. Linear positioning member  412  may generally include three regions: a tray coupling region  420 , a medial region  422 , and a divider region  424 . The tray coupling region  420  may include a tray coupling assembly  430  that is capable of coupling the linear positioning member  412  to upper tray  402 . In this manner, the linear positioning member  412  may be maintained in a generally fixed position relative to upper tray  402 . Tray coupling assembly  430  may include arms  432  that define a channel  438  therebetween. Upper tray  402  may include a projection or T-rail  434  (shown in  FIG. 13A ) that is suitably sized and shaped to be closely received into channel  438 . When the rail  434  is received into channel  438 , a tongue and groove or similar slot-type connection may be formed between linear positioning member  412  and upper tray  402 . When rail  434  is received in channel  438 , a suitable fastening means may be used to prevent longitudinal movement of the linear positioning member  412  relative to the rail  434  or disengagement of the linear positioning member  412  from rail  434 . Suitable fastening means include any methods known in the art such as rivets, bolts, screws, adhesives, staples or other suitable methods. The base portion of channel  438  may include recesses or a groove  440  to accommodate the head portion of a fastening means such as a rivet, screw, bolt, or other fastener. While a tongue and groove or similar slot-type connection has been discussed in some detail, linear positioning member  412  may be attached to upper tray  402  in any manner known in the art. Suitable means for attaching linear positioning member  412  to upper tray  402  include rivets, bolts, screws, adhesives, staples, or other suitable methods. 
     The medial region  422  is formed adjacent to the tray coupling region  420 . In one embodiment, the medial region  422  may be wider than the tray coupling region  420 . The portion of the outside surface  450  located within the medial region  422  may be generally arcuate or contoured. The contoured profile may improve the resistive properties of the medial region  422  as it is compressed. 
     The medial region  422  may include at least one longitudinal chamber  444 . The embodiment depicted in  FIG. 14  includes two side-by-side chambers  444 . It may be desirable to locate a portion of a longitudinal chamber  444  between each package  30  and upper tray  402 . Longitudinal chambers  444  may longitudinally traverse a portion of the linear positioning member  412 . In one embodiment, the longitudinal chambers  444  traverse the entire length of the linear positioning member. In another embodiment, the longitudinal chambers  444  are open at the ends of the linear positioning member  412 . In the embodiment depicted in  FIG. 14 , the longitudinal chambers  444  occupy the majority of the medial region  422 . In this embodiment, the medial region  422  may be considered generally hollow. The longitudinal chambers may have any cross-sectional shape such as circular, ovoid, square, rectangular, or arbitrary. The longitudinal chambers  444  depicted in  FIG. 14  are generally trapezoidal in shape but have an outwardly directed sidewall that is arcuate or contoured instead of linear. 
     The medial region  422  includes a package contact region  452  located along the outer surface  450  of the linear positioning member  412 . Along the package contact region  452 , the packages  30  will contact or abut a portion of the linear positioning member  412 . It may be desirable to include gripping projections or ridges  454  along a portion of the package contact region  452  to facilitate gripping the package  30  and reduce slippage of the package  30  relative to the linear positioning member  412 . It may be desirable to locate package contact regions  452  along a portion of the linear positioning member  412  near at least one of the longitudinal chambers  444 . Further, it may be desirable to locate the package contact region  452  along the thinnest portion of the linear positioning member  412  between the outside surface  450  and the inside surface of the longitudinal chamber  444 . 
     During agitation, the packages  30  may compress the medial region  422  of the linear positioning member  412  against upper tray  402 . Similarly, packages located closer to the upper tray  402  than the surface of the package contact region  452  will compress the linear positioning member  412  against upper tray  402 . In this manner, the linear positioning member  412  may hold packages located at various distances from the upper tray  402 . In some embodiments, as linear positioning member  412  compresses, the longitudinal chambers  444  may collapse somewhat. The thickness of the portion of the linear positioning member between the package contact region  452  and the inside wall of a longitudinal chamber  444  may determine the amount of force required to compress the chambers  444 . By varying the thickness of this portion the resilience of the linear positioning member  412  may be adjusted. 
     The divider region  424  is located adjacent to the medial region  422 . In one embodiment, the divider region  424  is located on the opposite side of the medial region  422  from the tray coupling region  420 . The divider region  424  may include a longitudinal divider projection or lip  448 . When the linear positioning member  412  is disposed between two packages, as depicted in  FIG. 13A , lip  448  may extend between the packages. Lip  448  may prevent the packages from contacting and possibly damaging one another. Lip  448  may be generally tapered in shape to facilitate the inserting of the lip in-between the packages positioned on the previous tray, when putting a new empty tray on the stack. The sloped edges of the lip  448  may also gently urge packages into position. As may best be viewed in  FIG. 13B , the lip  448  may extend longitudinally along a portion of the linear positioning member  412 . In one embodiment, the lip  448  occurs along the linear positioning member  412  at the locations where packages contact the linear positioning member  412 . In another embodiment, the lip  448  extends over the entire length of the linear positioning member. 
     The amount of force required to compress the linear positioning member  412  may also be determined by the material chosen to construct it. The linear positioning member  412  may be constructed from any suitable material including extruded silicon, silicon rubber, silicone foam-rubber, EPDM, polypropylene, or any elastic material (for example, perfluorinated elastomers and fluorinated copolymers) that can withstand a steam, steam-air, or steam-air-water environment at temperatures up to 130° C. In the preferred embodiment, the linear positioning member  412  may be formed from a material with a hardness of about 45 to 60 shore A. Referring to its cross-section, the linear positioning member  412  is approximately 10-40 mm wide and 10-30 mm tall. However, as apparent to one of ordinary skill, smaller or larger linear positioning members  412  may be constructed to accommodate packages of various sizes and/or weights. 
     Preferably, the linear positioning member  412  is long enough to span more than one row of packages  30 . Referring to  FIG. 13B , the linear positioning member  412  is depicted spanning at least four rows. In one embodiment, the linear positioning member  412  spans across all of the rows included in the retort drum. Therefore, the length of the linear positioning member  412  may be determined by the number of rows spanned or the size of the retort drum used. If the trays include a center support (depicted in FIGS.  16 D 1 - 3 ), it may be desirable to size the length of the linear positioning member to span from one edge of the tray to the middle support. 
     Referring to  FIG. 15 , it may also be desirable to include gripping projections or ridges  494  along the flexible pad  414 . Such gripping projections  494  may be desirable for use with any of the embodiments including a flexible pad. These gripping projections may help prevent scuffing of the underside of the package  30 . 
     Referring to  FIG. 16A , a front cross-sectional view of a retort drum  480 , into which upper tray  402  and lower tray  404  may be loaded with packages  30  therebetween, is depicted. As can be seen in  FIG. 16A , many trays may be vertically arranged within the retort drum  480 . Linear positioning members  412  are shown placed between each neighboring pair of packages within a horizontal row. 
     As mentioned in the Background, the trays are stacked on a carrier pallet  482 . FIG.  16 B 1  depicts an elevational top view of an exemplary carrier pallet  482  known in the art. FIG.  16 B 2  depicts a front view of carrier pallet  482  and FIG.  16 B 3  depicts a side view of carrier pallet  482 . Carrier pallet  482  includes a frame  486  for supporting the trays. The frame defines channels  488  into which the idler wheels may be received. 
     FIG.  16 C 1  depicts an elevational top view of an exemplary tray  404  known in the art. FIG.  16 C 2  depicts a front view of tray  404 , and FIG.  16 C 3  depicts a cross-sectional side view of tray  404 . Further, tray  404  may include a center support or flange  472  to increase the rigidity of the tray  404 . The embodiment of tray  404  depicted in FIGS.  16 C 1 - 3  includes upwardly extended slats  474 . These slats  474  may occur along opposing edges of the tray  404 . Further, these slats may occur along the edges orthogonal to the linear positioning members  412 . When a second tray is stacked on top of tray  404 , the upwardmost portion of the upwardly extending slats  474  may bear against a portion of the underside of the tray above tray  404 . The horizontal deck or web  483  of tray  404  may include perforations  470  for the process water to penetrate the complete stack and through-holes in center and side flanges  472  and  474  to reduce the weight of the tray. 
     Referring to FIGS.  16 D 1 - 3 , an optional pad  414  may be included on the package receiving surface of tray  404 . Pad  414  may include perforations that may be positioned adjacent to the perforations in the horizontal deck of the tray  404 . Pad  414  may also include divider projections  416  as discussed above relative to  FIGS. 13A and 13B . Rather than being in sections, the divider projections may extend the entire length of the pad  414 . 
     To reduce the height and/or weight of the stack it may be desirable to use a top tray that is shorter than tray  404 . FIGS.  16 E 1 - 3  depict orthogonal views of an exemplary top tray  490  known in the art. Top tray  490  includes a center support  472 ′ that is shorter but of the same general shape as center support  472  of tray  404 . Referring to  FIG. 16A , after the top tray  490  has been added to the stack, upper clamping plate  484  may be clamped to the top tray  490  on top of the stack. The carrier pallet  482  may be lifted to clamp the stack for processing inside the retort drum  480 . While exemplary embodiments of the carrier plate, tray, top tray, and clamping plate have been presented for illustrative purposes, it is apparent to those of ordinary skill in the art that other embodiments of these structures are within the scope of the present invention. 
     Referring to  FIG. 17 , a second embodiment of a linear positioning member  512  is depicted. Linear positioning member  512  may be formed from the same materials suitable to form linear positioning member  412 . Like linear positioning member  412 , linear positioning member  512  may include a tray coupling region  520 , a medial region  522  that is adjacent to the tray coupling region  520 , and a divider region  524  that is adjacent to the medial region  522 . Tray coupling region  520  may include a tray coupling assembly  530 . Tray coupling assembly  530  may include outwardly extending flanges  532  and  534 . In one embodiment, outwardly extending flanges  532  and  534  extend horizontally from the linear positioning member and may be coupled to the tray using any mechanism listed as suitable for fastening tray coupling assembly  430  to the tray. In one embodiment, silicon adhesive may be used to fasten linear positioning member  512  to the upper tray  402 . 
     Medial region  522  may include two longitudinal chambers  544 . In this embodiment, longitudinal chambers  544  have a generally circular cross-sectional shape. Further, the outside surface  550  of the medial region  522  may be contoured substantially similarly to the contour of the sidewalls defining longitudinal chambers  544 . Because the longitudinal chambers  544  have a generally circular cross-sectional shape and the outside surface  550  of the medial region  522  is contoured to substantially match the contour of the sidewall of longitudinal chamber  544 , the medial region  522  may take on the general appearance of two intersecting tube sections coupled side-by-side to each other. 
     The package contact region  552  may be formed along the outside surface  550  of the medial region  522 . In one embodiment, the package contact region  552  is located along the lower portion of the medial region farthest from the upper tray  402 . Like linear positioning member  412 , linear positioning member  512  may also include gripping projections (not shown) located along its outer surface  550  in the package contact region  552 . 
     The divider region  524  may include lip  548  similar to lip  458  above positioned near the intersection of the tube sections. The lip  548  may be located on the opposite side of the tube sections from tray coupling assembly  530 . The longitudinal chambers  544  of linear positioning member  512  are located on opposite sides of lip  548 . In this manner, each chamber  544  may be adjacent to a different package or row of packages. Further, each package may be adjacent to a unique section of one of the longitudinal chambers  544 . 
     Referring to  FIG. 18 , linear positioning member  812  may be viewed. Linear positioning member  812  includes many of the features present in the other linear positioning members described herein. Specifically, linear positioning member  812  may include a tray coupling region  820  that is integrally formed with medial region  822 . In some embodiments medial region  822  occurs beneath tray coupling region  820 . Linear positioning member  812  may also include a divider region  824  that is integrally formed with the medial region  822 . The divider region may be formed along the opposite side of the medial region  822  from the tray coupling region  820 . 
     The tray coupling region  820  may be generally consistent with the tray coupling region of linear positioning member  412  or any method known in the art suitable for coupling linear positioning member  412  to tray  404 . 
     The medial region  822  may include at least one longitudinal chamber  844 . In the embodiment depicted in  FIG. 18 , longitudinal chamber  844  is sufficiently large to consider linear positioning member  812  generally hollow. Further, the cross-sectional shape of the longitudinal chamber  844  may approximate the cross-sectional shape of the linear positioning member  812  along its outer surface  850 . In some embodiments, the linear positioning member  812  has a generally pentagonal cross-sectional shape. 
     The divider region  824  may include a divider projection  848 . In the embodiment depicted in  FIG. 18 , the divider projection comprises a tapered portion formed along the underside of the medial region  822 . The divider projection  848  functions to prevent packages  30  from contacting one another. Any materials suitable for forming the linear positioning member  412  may also be suitable for forming linear positioning member  812 . As with the other linear positioning members, the packages contact the divider projection  848  along a package contact region  852 . As the packages bear against the package contact regions  852  located along opposing sides of the divider projection  848 , the divider projection  848  may compress inwardly. 
     As the packages  30  exert an upwardly directed force against linear positioning member  812 , the medial region  822  may compress. Further, longitudinal chamber  844  may collapse somewhat to absorb some of the upwardly directed force. 
     In all of the aforementioned embodiments of the linear positioning member, a medial region was present that included at least one longitudinal chamber. However, it is apparent to those of ordinary skill in the art that the medial region may not necessarily include a longitudinal chamber. Further longitudinal chambers may be present in the divider region. In some embodiments the linear positioning member need only prevent the packages from coming into contact with one another. In those embodiments the linear positioning member need not contact the face of the package nearest the upper tray  402 . Referring to  FIG. 19A , one embodiment of such a linear positioning member is depicted. Generally speaking, linear positioning member  912  includes a tray coupling region  920  similar to that of tray coupling region  820  and a divider region  924  integrally formed with the tray coupling region  920 . The divider region  924  extends downwardly between two adjacent packages  30 . In the embodiment depicted in  FIG. 19A , the divider region is generally circular in cross-sectional shape and includes a longitudinal chamber  944 . Therefore, the divider region  924  may be generally tubular in shape. The generally tubular shape of the divider region  924  resists the movement of packages  30  toward one another. In this manner, the linear positioning member  912  maintains the packages within their desired positions. 
     If instead of a generally circular cross-sectional shape, the linear positioning member  912  had a generally tapered divider region, the tapered shape may facilitate loading packages between two adjacent linear positioning members. Referring to  FIG. 19B , a linear positioning member  1012  generally similar to linear positioning member  912  is depicted. The linear positioning member has a tray coupling region  1020  and a divider region  1024 . The dividing region  1024  of linear positioning member  1012  is tapered along its outside surface to facilitate loading. 
     Additionally, the tapered section need not include a longitudinal chamber. Instead, referring to  FIG. 19C , linear positioning member  1112  includes two tapered arms  1146  located on opposing sides of linear positioning member  1112 . In this manner, if packages  30  were to move vertically upward, arms  1146  could deflect inwardly toward the central axis of linear positioning member  1112 . The resistive properties of the material used to form linear positioning member  1112  may determine the amount of force necessary to deflect arms  1146 . Linear positioning member  1112  may be formed from any of the materials suitable for forming linear positioning member  412 . 
     Referring to  FIG. 20 , linear positioning members  1212  may be embedded in tray  404 . The horizontal web of trays  404  may include rails  434 ′ formed therein. Linear positioning member  1212  may include a longitudinal chamber  1244  suitably sized and shaped to receive rail  434 ′. A gap between the horizontal web and rail  434 ′ may be filled with a portion of linear positioning member  1212 . Two divider projections  1248 A and  1248 B may project outwardly from linear positioning member  1212 . In one embodiment, divider projection  1248 A extends upwardly to divide packages received on the package receiving surface of tray  404 . The other divider projection  1248 B extends downwardly. Divider projection  1248 B may extend downwardly between packages located in the tray beneath tray  404 . In this manner, linear positioning member  1212  may be used to maintain packages within a desired position both above and beneath the tray in which it is installed. 
     Referring to  FIG. 21 , a cross-sectional view of a further embodiment of a linear positioning member is depicted. Like the other embodiments of linear positioning members, linear positioning member  1612  may include an upper tray coupling region  1620 , a medial region  1622 , and a lower divider region  1624 . 
     The tray coupling region  1620  may include a tray coupling assembly  1630 . Tray coupling assembly  1630  may be of various configurations including any of the structures recited with regard to tray coupling assembly  430 . Further, tray coupling assembly  1630  may include a substantially planar upper surface that is fastened to tray  402  in any manner suitable to attach linear positioning member  412  to tray  402 . If fasteners with heads are used, a groove may be provided in the tray coupling assembly  1630 , similar to groove  440  of linear positioning member  412 . 
     The medial region  1622  includes a single longitudinal chamber  1644 . In one embodiment, longitudinal chamber  1644  is sufficiently large to consider both the medial region  1622  and the divider region generally hollow. Because those sections are generally hollow, a substantially uniform sidewall is formed between the longitudinal chamber and the outer surface  1650  of the linear positioning member  1612 . Pressure exerted by either package resting on opposite sides of the divider region  1624  will deform the sidewall of longitudinal chamber  1644 . As with other embodiments, varying the thickness of the sidewall can determine the load required to deform the sidewall. 
     Divider region  1624  may include a divider projection  1648  that extends downwardly between two adjacent packages. In one embodiment, the contoured outside surface of the divider projection  1648  is inwardly concave along opposite sides of the projection  1648 . The divider projection  1648  may also be generally tapered in shape with a distal portion that is narrower than the portion adjacent to the medial region  1622 . In this embodiment, the package contact region  1652  is located along the contoured outside surface of the divider region  1624 , providing a curved surface against which package  30  will bear. Further, the distal center portion of the divider projection  1648  may include a contoured (upwardly concave) resilient section  1656  to resist inward forces from the packages abutting the package contact regions  1652  on opposite sides of the divider projection  1648 . Resilient section  1656  may also position the package contact region to bear against a portion of the side face of the package so that lateral movement of the package is limited. Further, flexing and distortion in the general direction of the divider projection  1648  may be resisted. 
     Linear positioning member  1612  may be approximately 15-30 mm and preferably about 18.5 mm tall. Linear positioning member  1612  may be approximately 15-40 mm and preferably about 25 mm wide. However, it is appreciated by those of ordinary skill in the art that these dimensions may be increased or decreased to accommodate packages of various sizes and weights. Linear positioning member  1612  may be formed from the same materials suitable to form linear positioning member  412 . Linear positioning member  1612  may also be as long as linear positioning member  412 . 
     Referring to  FIG. 22 , a cross-sectional view of another embodiment of a linear positioning member is depicted. Linear positioning member  1712  may include the following regions: a tray coupling region  1720 ; a medial region  1722  that may be located below and integrally formed with the tray coupling region  1720 ; and a divider region  1724  that may be located below and integrally formed with the medial region  1722 . 
     Tray coupling region  1720  may include a tray coupling assembly  1730 . Any tray coupling assembly suitable for use with linear positioning member  1612  is likely also suitable for use with linear positioning member  1712 . Similarly, longitudinal grooves may be included to accommodate the heads of fasteners if heads are present. 
     The medial region  1722  of this embodiment may be relatively small in relation to the divider region  1724  (discussed below). Medial region  1722  includes a longitudinal chamber  1744  that may be substantially similar to the longitudinal chambers of the previous embodiments. In one embodiment, the longitudinal chamber  1744  is sufficiently large to consider the medial region  1722  generally hollow. Like other embodiments described herein, the outside surface  1750  of the medial region  1722  may be curved and/or contoured to resist compression. Portions of the sidewalls of the longitudinal chamber  1744  may be contoured to substantially mirror the contours of the outside surface of the side portions of the medial region  1722 . 
     The divider region  1724  is located below the medial region  1722 . The divider region  1724  includes a divider portion  1748  that may longitudinally traverse a portion of the linear positioning member  1712 . Divider portion  1748  includes two forked or bifurcated projections  1760  and  1761 . Each forked projection is designed to deflect when forces are exerted upon it by a package  30 . Forked positioning projection  1760  deflects in the general direction of arrow  1762 . The direction of deflection of forked positioning projection  1761  is generally depicted by arrow  1764 . The tines  1770 ,  1772  of the forks may intersect at approximately a 85° to 95° and preferably a 90° angle to form a shoulder  1766 . 
     Packages  30  bear against shoulder  1766 . Preferably, the intersection of two faces of the package will be received within the shoulder  1766  so that a portion of one face of the package  30  contacts the package contact region  1752  of one tine and a portion of the other face of the package contacts the package contact region  1752  of the other tine. In this manner, one tine  1770  of the forks may maintain the vertical position of the package  30  and the other tine  1772  may maintain the horizontal position of the package  30 . Forks  1760  and  1761  may be approximately 8-12 mm and preferably about 10 mm wide. Further, forks  1760  and  1761  may be approximately 8-12 mm and preferably about 10 mm in height. Forks may extend longitudinally along a portion of the linear positioning member  1712  or along the entire length of the linear positioning member  1712 . 
     When force is applied to one of the forks ( 1760  or  1761 ), such as by a package  30  during agitation, the force may cause the fork to deflect, compress, or be pushed toward longitudinal channel  1744 . Longitudinal channel  1744  may collapse somewhat to absorb some of the force exerted by the package upon the fork. In this manner, the linear positioning member  1712  may offer a large deflection with minimal change in force applied to the package  30 . 
     Linear positioning member  1712  may be approximately 20-40 mm and preferably about 30 mm wide. Further, linear positioning member  1712  may be approximately 20-30 mm and preferably about 25 mm in height. Linear positioning member  1712  may be formed from any suitable material including materials suitable to form linear positioning member  412  above. Linear positioning member  1712  may be of a similar length to linear positioning member  412 . 
     Referring to  FIG. 23 , linear positioning member  1912  is provided. Linear positioning member  1912  includes a tray coupling region  1920  integrally formed with medial region  1922 . Integrally formed with medial region  1922  on the opposing side from the tray coupling region  1920  is the divider region  1924 . Tray coupling region  1920  may be generally similar to the other tray coupling regions previously disclosed. Further, medial region  1922  may be generally similar to the other medial regions disclosed previously. Specifically, medial region  1920  may be generally hollow including a longitudinal chamber  1944 . The outside surface  1950  of the linear positioning member  1912  along the medial region  1922  may be generally curved to resist compression. The bottom portion of the medial region  1922  may include a nominally angled surface  1930  that may be at an angle ranging from about 10 to about 20 degrees from horizontal and preferably about 15 degrees from horizontal. The outer surface  1950  of the medial region  1922  may include a portion  1932  that is generally parallel to surface  1930  when in use. In this manner, when a package is placed against outer surface  1932 , a substantially horizontal face of the package may exert an upward force on outer surface  1932  urging it upward toward tray  402 . The divider region  1924  may include a downwardly projecting divider projection  1948 . Divider projection  1948  may be integrally formed with the lower portion of the medial region  1922 . Divider projection  1948  may form a nominal angle β ranging from about 10 to about 20 degrees and preferably about 15 degrees from vertical. In this manner, the portion of the outer surface  1932  and projection  1948  may form approximately a 90 degree angle. As the horizontal surface  1932  is pushed upwardly by a package, projection  1948  rotates or deflects in the general direction of arrow  1962 . As divider projection  1948  rotates, it may bear against the side surface of package  30 . In this manner, the surface  1932  may resist further upward movement of package  30  and the divider projection  1948  may resist lateral movement of the package  30 . 
     Referring to  FIG. 24 , a further embodiment of the present invention is illustrated. The linear positioning member  2012  shown in this figure includes a coupling region  2020  and a resilient region  2022  disposed below the coupling region. The linear positioning member  2012  is secured to the underside of tray  2024  by a coupling assembly  2030 . The coupling region  2020  includes a central entrance channel portion  2026  that extends downwardly from the upper end of the linear positioning member to intersect a wider slot  2028  that is undercut beneath shoulder portions  2032  of the positioning member coupling region  2020 . The slot  2028  is sized to closely receive a retaining bar  2034  therein. The retaining bar is wider than the width of the entrance channel  2026 , and thus is held captive within the slot  2028 . 
     The linear positioning member  2012  is retained against the bottom side of the tray  2024  by the coupling assembly  2030 , which includes a bolt  2036  that extends upwardly through a clearance hole formed in the retaining bar  2034  through a clearance hole formed in the tray  2024 , as well as through the center of a tubular spacer  2038  to threadably engage with a locking nut  2040 . A retaining nut  2042  threadably engages with the shaft portion of the bolt  2036  to hold retaining bar  2034  in place. It will be appreciated that during initial assembly, a gap exists between the upper surface of the retaining nut  2042  and the lower surface of tray  2024 . However, when the locking nut  2040  is fully tightened, the shoulder portions  2032  of the coupling region  2020  are tightly clamped between the retaining bar  2034  and the perforated tray sheet  2024 , until the upper surface of the nut  2042  bottoms against the tray. In this regard, please see  FIG. 27 . The tubular spacer  2038  has a length that corresponds to the thickness of the resilient pad  2044 . It will be appreciated that by the foregoing construction the linear positioning member  2012  is securely held in place by a series of coupling assemblies  2030  spaced along the length of tray  2024 . It will also be appreciated that the retaining bar  2034  may coextend with the length of the linear positioning member. Alternatively, the retaining bar  2034  could be composed of shorter lengths or individual pieces, as desired. 
     As shown in  FIG. 24 , the general shape of the linear positioning member resembles a truncated triangle that tapers outwardly in the downward direction. The resilient region  2022  of the linear positioning member is generally bulbous, and may be composed of three separate cavities, a left-hand cavity  2050  of generally circular cross-section and a right-hand cavity  2052  also of generally circular cross-section. A generally rectilinear central cavity  2054  may be positioned between the left and right cavities  2050  and  2052 . It will be appreciated that the cavities  2050 ,  2052  and  2054  cooperatively cause the resilient region  2022  to exert a force on a package  30 . One such package is placed against the outer surface  2056  of the linear positioning member  2012 . The linear positioning member  2012  may be composed of flexible, compressible material in the manner of the linear positioning members discussed above. Such materials could include, for example, silicone rubber, silicone foam rubber, EPDM, polypropylene or other elastic material (for example, perfluorinated elastomer or fluorinated copolymers) that can withstand steam, steam-air, or similar environment at temperatures up to about 130° Centigrade. 
     It will also be appreciated that the resilient region  2022  can be constructed in other configurations without departing from the spirit or scope of the present invention. For manufacturing reasons, it is advantageous that the thicknesses of the walls comprising the cavities  2050 ,  2052 , and  2054  are of approximately uniform thickness, though this is not absolutely essential. 
     An example of a differently configured resilient region is shown in  FIG. 25 . The positioning member  2112  depicted in  FIG. 25  is shaped similarly to linear positioning member  2012  but with a resilient region  2122  of somewhat different configuration. The resilient region  2122  includes a relatively large generally ovoid central cavity  2154 , and relatively smaller outer cavities  2150  and  2152 . With this exception of the construction of the resilient region  2122 , the positioning member  2112  of  FIG. 25  could be constructed very similarly to the linear positioning member  2012  of  FIG. 24 . In this regard, a coupling assembly  2130  is utilized to mount the positioning member  2112  to tray  2124 . The coupling assembly is shown in fully tightened condition. 
       FIG. 26  discloses a resilient positioning member  2212  constructed somewhat similarly to positioning members  2012  and  2112 . In this regard, the positioning member  2212  includes a coupling region  2220  similar to coupling regions  2020  and  2120  shown in  FIGS. 24 and 25 , as well as a resilient region  2222 , which may be similar to resilient regions  2022  and  2122  shown in  FIGS. 24 and 25 . 
     For the embodiment of the present invention shown in  FIG. 26  the coupling region  2220  of the linear positioning member  2212  may be constructed similarly to the coupling regions  2020  and  2021  of the positioning members  2012  and  2112 . The resilient region  2252 , however, is constructed somewhat differently than the resilient regions  2022  and  2122  of the linear positioning members  2012  and  2112 . In this regard, the resilient region  2252  includes generally teardrop-shaped left-hand  2250  and right-hand  2256  hollow cavities, providing for the resilient compressibility of the linear positioning member. The cavities  2250  and  2256  may be separated by a thin medial wall  2222 . The resilient region  2252  also includes a central lower, generally triangularly shaped cavity  2254  positioned beneath and between the left-hand and right-hand cavities  2250  and  2256 . As in the linear positioning members  2012  and  2112 , the cavities  2250 ,  2256  and  2254  may be formed by wall sections of substantially uniform thickness. As can be appreciated, when the linear positioning member  2212  is pressed against a container  30 , the resilient region  2252  is capable of resilient deformation while applying a reactionary load against the container  30  similar to the manner of the other linear positioning members of the present invention described above. It is expected that the linear positioning member  2212  may be somewhat more stable in the side-to-side or lateral direction when deformed when pressed against a container  30  relative to the linear positioning members  2012  and  2112 . 
       FIG. 26A  illustrates a resilient positioning member  2260  constructed somewhat similarly to positioning member  2212  shown in  FIG. 26 . In this regard, the positioning member  2260  includes a coupling region  2262 , a resilient region  2264  and a divider region  2266 . Coupling region  2262  may be constructed similarly to coupling region  2220  of linear positioning member  2260 , and thus its description will not be repeated here. The resilient region  2264  is constructed somewhat differently than the resilient region  2252  of linear positioning member  2212 . In this regard, the resilient region  2264  includes generally teardrop-shaped left-hand  2248  and right-hand  2270  hollow cavities, allowing for the resilient compressibility of the linear positioning member. These two cavities are separated by a central, lower, generally rounded, triangularly shaped cavity  2271 . The upper apex portion of cavity  2271  intersects a nipple portion  2272  that extends downwardly from the coupling region  2262 , thereby to separate the left-hand  2248  and right-hand  2270  cavities from each other. As in the linear positioning member  2212 , the cavities  2248 ,  2270  and  2271  may be formed by wall sections of substantially uniform thickness. However, these linear position members can also be constructed with wall sections of varying thickness so as to arrive at a desired structural composition. As will be appreciated, when the linear positioning member  2260  is pressed against a container  30 , the resilient region  2264  is capable of resilient deformation while applying a reactionary load against the container, similar to the manner of the other linear positioning members of the present invention, described above. 
     The divider region  2266  is located downwardly adjacent the resilient region  2264 . As in other embodiments of the present invention described above, the divider region  2266  may include a longitudinal divider projection or lip  2274 . When the linear positioning member  2260  is disposed between two packages, the lip  2274  may extend between the packages, thereby preventing the packages from contacting and possibly damaging one another. The lip  2274  may be downwardly tapered to facilitate the insertion of the lip in between the packages positioned on the previous (lower) tray when putting a new empty tray on the stack. The sloped edges of the lip  2274  may also gently urge the packages into correct position. The lip  2274  may extend along the entire length of linear positioning member  2260 . Alternatively, the lip may only extend along the linear positioning member  2260  at locations where packages contact a linear positioning member. 
     Also, the linear positioning member  2260  may include gripping projections or ridges  2273  along a portion of the resilient region  2264  that contacts a packaging  30 . The gripping projections or ridges  2273  may facilitate the gripping of the packages  30  and reduce slippage of the packages relative to the linear positioning member. 
       FIG. 26B  illustrates a resilient linear positioning member  2280  constructed similarly to linear positioning member  2260 , described above. In this regard, the linear positioning member  2280  includes a coupling region  2282 , a resilient region  2284  and a divider region  2286 . The coupling region  2282  and the divider region  2286  are similar to the corresponding regions of the linear positioning member  2260 , thus these regions will not be described in detail. Rather, corresponding components of these regions are given the same part number as in  FIG. 26A , but with the addition of “B” suffix. The resilient region  2284  does differ somewhat from the resilient region  2264  of the linear positioning member  2260  shown in  FIG. 26A . In this regard, the resilient region  2284  includes left-hand  2288  and right-hand  2290  hollow cavities extending lengthwise of the linear positioning member  2280 . The upper and lower margins of such cavities are substantially parallel, whereas the outer perimeter of such cavity corresponds to the outer perimeter of the resilient region  2284 . The inner perimeter of the cavities  2288  and  2290  form a portion of a circle corresponding to the diameter of a central cavity  2291  that divides the left-hand  2288  and right-hand  2290  cavities from each other. The central cavity  2291  has a diameter closely corresponding to the height of the cavities  2288  and  2290 , as shown in  FIG. 26B . As will be appreciated, when the linear positioning member  2280  is pressed against the container  30 , the resilient region  2284  is capable of resilient deformation while applying a reactionary load against a container, similar to the manner of the other linear positioning members of the present invention as described above. 
       FIG. 26C  illustrates a further resilient linear positioning member  2292  constructed similarly to linear positioning member  2280 , described above. In this regard, the components of the linear positioning member  2292  that are similar to that of linear positioning member  2280 , shown in  FIG. 26B , are given the same number as in  FIG. 26B , but with a “C” suffix. Thus, as in linear positioning member  2280 , the linear positioning member  2292  includes a coupling region  2282 C, resilient region  2284 C, and a divider region  2286 C. The coupling region  2282 C and divider region  2286 C are similar to corresponding regions of the linear positioning member  2282 . These regions will not be described in detail. 
     The resilient region  2284 C does differ somewhat from the resilient region  2284  of the linear positioning member  2280 , shown in  FIG. 26B . In this regard, the lower portions of the left-hand  2288 C and right-hand  2290 C hull cavities, in cross-section, extend generally tangentially downwardly from the maximum outer wall diameter of the central cavity  2291  C, thereby to define a thicker intersection region  2294  than in the corresponding portion of the resilient region  2284  of the linear positioning member  2280 . This thicker intersection region adds a certain level of structural integrity to this portion of the linear positioning member  2292 . 
       FIG. 27  is a fragmentary side elevational view similar to FIGS.  16 C 3  and  16 D 3  showing the linear position members  2012  ( FIG. 24 ) installed on tray  2024 . The tray  2024  includes a base, having a horizontal web  2060  and side slats  2062 . As in the trays shown in FIGS.  16 C 3  and  16 D 3 , the side slats  2062  may have a series of apertures  2064  formed therein to reduce the overall weight of the tray  2024 . 
     Rather than utilizing a flexible pad over the entire web  2060 , for example, flexible pad  414  shown in FIG.  16 D 3 , the embodiment of  FIG. 27  utilizes strips  2066  of flexible padding material running along the length of the linear positioning members  2012 . Such strips  2066  may be composed of the same material utilized to form flexible pad  414 . Use of the strips  2066  rather than a pad covering the entire area of web  2060 , serves to reduce the overall weight and cost of the package holder shown in  FIG. 27 . 
     As also shown in  FIG. 27 , strips  2066  may include divider projections  2068  that extend upwardly above the upper surface of the strips  2066  and also extend across the width of the strips. As in divider projections  416 , discussed above, the divider projections  2068  function to help retain the containers  30  in place in the direction perpendicular to the strips  2066  and also longitudinal projections  2069  in the direction of the strips  2066 . 
       FIGS. 27A ,  27 B and  27 C illustrate a top plan view, a side elevational view and a side cross-sectional view of the tray  2024  of  FIG. 27 . As will be apparent, the tray  2024  is similar in construction to the trays shown in FIGS.  16 C 1 ,  16 C 2 ,  16 C 3 ,  16 D 1 ,  16 D 2 , and  16 D 3 . However, one difference is that the lower flange portion  2070  shown in  FIG. 27C  is a continuous flange across the entire width of the tray, whereas in FIGS.  16 C 3  and  16 D 3 , such flange portion is broken up into sections. As in the trays shown in FIGS.  16 C 1 ,  16 C 2 ,  16 C 3 ,  16 D 1 ,  16 D 2 , and  16 D 3 , the tray of  FIGS. 27A ,  27 B and  27 C utilizes a center divider stiffener  2072  that extends across the middle of the tray  2024  to add significant rigidity to the tray structure. The stiffener  2072  extends upwardly from the horizontal web  2060  to a height corresponding to the height of the side slats  2062 . 
     A further embodiment of the present invention is illustrated in  FIGS. 28 and 29 , wherein is shown a tray  2300  which may be constructed similarly to trays  404  shown in FIGS.  16 C 1 ,  16 C 2 ,  16 C 3 ,  16 D 1 ,  16 D 2  and  16 D 3 . However, tray  2300  is designed to be used without the optional pad  414 . In this regard, ridges  2302  are formed in the web  2304  of the tray, which web may be perforated as in the webs of trays  404  shown in FIGS.  16 C 2  and  16 D 2 . The ridges  2302  serve to separate and position the packages  30  on the tray  2300  and relative to positioning member  2312 . The tray web  2304  may be constructed with upwardly extending elongated dimples  2306  that function to help position packages  30  in the direction along the length of ridges  2302 , performing a function similar to divider projections  416 , discussed above. The dimples  2306  may be formed by deforming the material comprising web  2304  in the upward direction in a manner well known in the art. 
     The positioning member  2312  may be attached to the underside of web  2304  utilizing a coupling assembly  2330  similar to coupling assemblies  2030  and  2130 , discussed above with respect to  FIGS. 24 and 25 . In this regard, the coupling assembly  2330  may utilize a retaining bar  2334  held captive within slot  2328  by a bolt  2336  and a retaining nut  2342 . The bolt extends through a clearance hole formed in ridge  2302  to engage with a washer  2339  and a lock nut  2340 . As apparent, the linear positioning member  2312  is constructed similarly to the linear positioning member  2012  shown in  FIG. 24 , with the exception that a tapered shoulder  3242  is formed in the distal upper end portion of coupling region  2320  to match the corresponding profile of the underside of ridges  2302  whereby the linear positioning member  2312  mates snugly with the underside of the ridges  2302 . 
       FIGS. 30 and 31  depict a further embodiment of the present invention, wherein a linear positioning member  2412  is mounted to the underside of the web portion  2414  of tray  2404 . As in the other linear positioning members of the present invention described above, the linear positioning member  2412  includes a coupling region  2420  adjacent the underside of web portion  2414 , a medial region  2422  designed to press against the top surfaces of container  30  and which is resiliently deformable, and a lower divider region  2424  which serves to retain the containers  30  in a desired position on the tray  2404 . Referring specifically to  FIG. 31 , the coupling region  2420  and the medial region  2422  of the linear positioning member  2412  may be essentially the same as in  FIG. 26 , and thus the components of these regions are given the same part numbers as in  FIG. 26 , but with the addition of a prime designation. 
     The linear positioning member  2412 , as noted above, also includes a divider region  2424 , which may be similar in construction to the divider region  424  shown in  FIG. 14 , whereby the divider region  2424  also includes a downwardly projecting member or lip  2448  that extends between adjacent packages  30  to prevent the packages from contacting each other and possibly damaging each other. The lip  2448  may be tapered in a downward direction to facilitate the loading of packages onto the trays  2404 . The sloped edges of the lip  2448  may also gently urge the packages into proper position. As shown in  FIG. 30 , the lip may extend longitudinally along the linear positioning member  2412  coextensive with the length of the medial region  2422 . 
     As in the embodiment shown in  FIG. 27 , the tray  2404  may include resilient strips  2440  that overlie the tray web  2414 . The resilient strips  2440  may be used in lieu of utilizing a full coverage mat to overlie the tray medial portion  2414 . Also as in  FIG. 27 , the resilient strip  2440  includes upwardly extending divider projections  2442  extending transversely across the strip  2440  and spaced apart to coincide with the width of the containers  30 . As shown in  FIG. 30 , the divider projections  2442  are tapered toward their extremities so as to serve as guides for positioning the packages  30  between two adjacent projections or ridges. Moreover, clearance holes  2444  are formed in all or part of the ridges  2442  for reception of hardware members or other means used to affix the strips to the tray  2404  and also to mount the linear positioning members  2412  in place beneath the tray web  2414  using hardware members or other convenient means. It will be appreciated that the present invention shown in  FIGS. 30 and 31  provides the same significant advantages provided by the other embodiments of the present invention discussed above. 
       FIGS. 32 and 33  depict a further embodiment of the present invention wherein a positioning system  2500  is illustrated as including a resilient upper holder  2502  that is attached to the underside of a web portion  2504  of tray  2506 . The holder  2502  corresponds to the shape of the adjacent face or wall of container  30  which is held in place between upper tray  2506  and lower tray  2508  through the holder  2502 . The holder  2502  is formed with an upwardly extending recess  2510  that is shaped to closely correspond to the shape of the adjacent face or surface of the container  30 . Such recess  2510  is defined by an outer rim portion  2512  that extends around the perimeter of the holder  2502 . The inside edge  2514  of the rim portion  2512  is flared outwardly in a downward direction so as to serve as a guide or lead-in for the adjacent surface of the package  30 . 
     The holder  2502  may be made from resilient deformable material which is capable of applying a load against the adjacent surface of the container  30  when the upper tray  2506  is lowered in place over the lower tray  2508 . Of course, if trays  2506  and  2508  can be constructed with sufficient precision, it may not be necessary to construct the holder  2502  from resilient material; rather, the holder could be constructed from non-resilient material or material that is only slightly resilient. It will be appreciated that by this construction the holder  2502  is capable of retaining the containers  30  securely in place without requirement of a holding mechanism on the opposite side of container  30  or even guides or dividers for the lower tray  2508  in a manner of, for example, ridges  2302  or elongated dimples  2306  shown in  FIGS. 28 and 29 . 
       FIGS. 32 and 33  illustrate the holder  2502  as used in conjunction with a singular container  30 . However, holders similar to  2502  may be of larger size and configured to hold several packages  30  in place at the same time. Such larger holder might be formed with multiple cavities similar to  2510  for closely receiving the adjacent surface of the package  30 . Such cavities may be separated by dividers similar to dividers  2512  shown in  FIGS. 32 and 33 . 
       FIG. 34  depicts a further embodiment of the present invention, wherein a positioning system  2600  is illustrated as including a resilient positioning member  2602  disposed within a restraining member  2604 . The linear positioning member  2602 , as in other embodiments of the present invention described above, may include a coupling region  2606 , a resilient region  2608  and a divider region  2610 . The coupling region  2606  and divider region  2610  may be similar to the corresponding regions of other linear positioning members of the present invention, for instance, as shown in  FIGS. 26A and 26B , thus the construction of these regions of the resilient positioning member  2602  will not be repeated here. 
     The resilient region  2608  may be constructed in the form of bellows having corrugated-shaped sidewalls  2612  and a substantially flat bottom wall  2614 . Grouping projections or ridges  2616  may be provided along the lower surface of the resilient region  2608 . As in other embodiments of the present invention, such projections or ridges help to securely grip the package  30 . 
     The restraining member  2604  may be generally U-shaped, having a web portion that is sandwiched between the upper surface of the coupling region  2606  and the underside of tray  2618 . The restraining member  2604  also includes side flanges that are positioned closely outwardly of the bellows sidewalls  2612 . In use, when the linear positioning member  2602  is pressed against a container, the resilient region  2608  is capable of retracting into the restraining member  2604 , while applying a reactionary load against the containers being held, similar to the manner of the other linear positioning members of the present invention described above. Moreover, the restraining member serves to provide lateral stability to the linear positioning member. Although not shown, the distal lower ends of the side flanges of the restraining member may be bent outwardly so as to define a “lead-in” for the sidewalls  2612  of the linear positioning member. As another aspect of the present invention, when the linear positioning member is fully retracted, preferably the lower surface of the resilient region will extend downwardly slightly below the lower edges of the restraining member flanges so that such flanges do not contact or damage the container  30  being held in place. As will be appreciated, the positioning system  2600  shown in  FIG. 34  provides the same advantages provided by the other linear positioning members of the present invention described above. 
       FIG. 35  illustrates a further resilient, linear positioning member  2700  constructed in accordance with the present invention. Linear positioning member  2700  is constructed similarly to several of the other linear positioning members described above, including those illustrated in  FIGS. 26A ,  26 B and  26 C. In this regard, the linear positioning member  2700  includes a coupling region  2702 , a resilient region  2704 , and a divider region  2706 . The coupling region  2702  is similar to the coupling region  2284  corresponding to the linear positioning member  2280  shown in  FIG. 26B , thus this region will not be described in detail. The resilient region  2704  does differ somewhat from the resilient regions of the linear positioning members shown in  FIGS. 26A ,  26 B and  26 C. In this regard, the resilient region  2704  includes left-hand ( 2708 ) and right-hand ( 2710 ) hollow cavities extending lengthwise of the linear positioning member. The upper and lower margins of such cavities are substantially parallel, whereas the outer perimeter of such cavities correspond to the outer perimeter of the resilient region  2704  and are generally semi-circular in shape. The upper portion of the inner perimeter of the cavities  2708  and  2710  form a portion of the generally semi-circular central cavity  2712  that separates the corresponding portion of the left-hand  2708  and right-hand  2710  cavities from each other. The left-hand  2708 , right-hand  2710  and central  2712  cavities intersect above the central cavity  2712  beneath a nipple portion  2714  that extends downwardly from the rail channel  2716 . 
     The section of the coupling region  2704  located below central cavity  2712  is essentially solid in structure with the exception of a central hole  2718  extending therethrough. The bottom of the through-hole  2718  is actually below the elevation of the exterior lower surface  2720  of the resilient region, and thus extends downwardly into the divider region  2706 . As in several of the other embodiments of the present invention described above, the divider region  2706  may include a longitudinal divider projection or lip  2722  that extends along the length of the linear positioning member  2700 . When the linear positioning member  2700  is disposed between two packages, the lip  2722  may extend between the packages, thereby preventing the packages from contacting and possibly damaging one another. The lip  2722  may be downwardly tapered to facilitate the insertion of a lip in between the packages positioned on a below-located tray when putting a new empty tray on top thereof. The sloped edges of the lip  2722  may also gently urge the packages into correct position. The intersection between the sides of the lip  2722  and the bottom surface  2720  of the resilient region is in the form of a diagonal fillet  2724 , which fillet also defines the wall section for the adjacent portion of the circular through-hole  2718 . 
       FIGS. 36 and 37  illustrate the linear positioning member  2700  mounted on a tray  2730 . As in the other trays of the present invention described above, the tray  2730  includes a base having a horizontal web  2732  and side slats  2734 . The tray also includes a central support flange  2736  which helps to increase the rigidity of the tray  2730 . 
     The linear positioning member  2700  is illustrated as mounted to the underside of the web  2732  in the same manner as the mounting of other linear positioning members of the present invention, for instance see  FIG. 31 . As also shown in  FIGS. 36  and  37 , a restraining bar  2740  may extend through the close-fitting circular through-hole  2718  formed in the linear positioning member  2700 . Vertical slots  2742  are formed in the slats  2734  as well as in the central flange  2736  to allow for vertical movement of the rod  2740  as the linear positioning member  2700  may be compressed, for example, when pressing against the adjacent portion of a package. However, the slots  2742  are sufficiently narrow to not allow significant side to side motion of the rod  2740 . The rod is held captive within circular opening  2718  by an enlarged circular section  2744  that has an outer diameter which is larger than the diameter of the circular through-hole  2718 . Thus, the rod  2740  is only allowed movement along its length corresponding to the difference between the length of the gap  2746  between adjacent end portions of the linear positioning members  2700  and the length of the enlarged section  2744 . Such movement is not sufficient to permit the ends of the rod  2740  to disengage from slat slots  2742 . 
     It will be appreciated that through the present invention, the resilient positioning members  2700  are able to exert a load on containers, such as container  30 , by the upward compression of the linear positioning members. At the same time, the linear positioning members are laterally stabilized by rod  2740 , which in turn minimizes the lateral movement of the containers being held in place by the linear positioning member  2700 . 
     It is apparent to those of ordinary skill in the art that while discrete embodiments of linear positioning members have been provided that many of the features presented with each embodiment may in fact be combined with other embodiments. For example, the divider regions of linear positioning members  19 A- 19 C and  20  may be readily adapted to serve as support members for the side faces of the packages that they extend between. Particularly, the divider regions may be widened or the angle of their taper lessened so that a larger portion of the divider projection rests against the side surfaces of the adjacent packages. In this manner the side surfaces of the packages are supported, and flexing of the faces of the packages is limited by the divider projections. It is further apparent to those of ordinary skill in the art that such modified divider projections may be included on any of the embodiments disclosed herein. In particular, these modified divider projections may be included on the embodiments depicted in  FIGS. 14 and 17 . 
     While the preferred embodiment of the invention has been illustrated and described, it will be appreciated that various changes can be made therein without departing from the spirit and scope of the invention.