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BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a sliding door assembly wherein the sash of the door seals against the door frame. 
     2. Background of the Prior Art 
     The main function of a building&#39;s envelope is to prevent water penetration into the interior of a building where such water can cause substantial damage. One problem in any envelope design is the junction between two or more items made from dissimilar materials such as where doors and windows integrate with the main building facade. As the two items are made from different materials, each material thermally expands and contracts at a different rate placing stress on the boundary joint of the two items. Caulks having a high coefficient of expansion and other techniques are used to address this problem. The caulks expand and contract and help modulate the expansion and contraction of the materials to which they are deposited upon. 
     Operable windows are another problem area in building moisture intrusion. By definition, when a window is open, access is provided into the interior of the building. Therefore, once the window is closed it must provide a moisture barrier for the building. Windows that swing out to open, similar to doors, press up against a peripheral flange on the window frame, which flange has a gasket thereon, which seals the sash of the window against the frame providing the moisture barrier. In the case of an in-swing door, wherein the bottom of the door does not press up against a sealing flange, appropriate rubber sweeps are placed along the bottom of the door in order to block moisture penetration therepast and the threshold is angled outwardly in order to channel any residual moisture back out. 
     Sliding windows present another problem in dealing with moisture penetration. As the window must slide up and down in a track, the window cannot press against a sealing flange like a swing window. As the window only presses up against one side of its sash, this is the only side where it is possible to have a press seal against the frame. The opposing side, where the sash typically interacts with another sash, which other sash may be fixed or movable, a gasket is provided on one of the sashes in order to provide a barrier between this junction. While such a gasket is not as formidable as a press seal, this junction is constructed such that the upper sash is oriented outwardly relative to the lower sash so that any moisture that challenges this gasket seal must travel upwardly to get to this seal. While it is possible to have storms that have winds that drive rain upwardly, the vertical vector component of such winds are not very large, therefore, the rain acts on the gasket with only a relatively small force, which the gasket handles. Additionally, such storms are very infrequent so that the gasket is not subject to frequent substantial challenges. 
     The sides of the window wherein the sash rides in a track pose a different problem. As the sash must travel up and down along this track, an airtight seal between sash and frame along the track is not possible. However, the tolerances between the sash and the frame are very tight so that most if not all moisture is stopped at the junction of sash and frame. For any moisture that bypasses this junction, the frames typically have a flanging system that deflects the water and channels the water back to the outside. 
     The problems associated with moisture barrier protection for horizontal sliding windows and more particularly sliding glass doors is much more challenging. The junction between two closed sashes on a sliding glass door is vertical. Therefore, the gasket that seals the junction between the two sashes is subject to rain any time the wind blows from the appropriate direction during a storm and as the door is at ground level, the lower part of the junction is subject to a rain load almost every shower due to the rain hitting the ground proximate the sash and splashing against the seal. Additionally, the flanging systems used on the windows to deflect moisture that passes the sash-frame contact area cannot be effectively used on the lower part of the door. As people must be able to pass through the door, the lower threshold must be kept to a reasonably short height in order to adequately facilitate walking therethrough. This height restriction is set not only by the desired comfort level of users of the door, but also by the Americans with Disabilities Act which sets upper height restrictions on all new construction sliding doors. Therefore, vertically disposed flanging systems that are commonly found on hung windows, which systems tend to be relatively wide, cannot be effectively deployed on a sliding glass door that has threshold height restrictions and which also requires that the threshold be subject to the forces associated with people walking thereon. Accordingly, moisture barrier systems found on sliding doors tend to be less reliable relative to other door and window moisture barrier systems. 
     The flanging systems found on current sliding doors tend to have multiple spaced apart flanges in order to accommodate the tracks upon which each sash of the door slides and to act as rain barriers. Such a multiple flange configuration, even though it is relatively low in height, is somewhat uncomfortable to walk across and is difficult to bypass in a wheelchair that must pass across the several flanges. 
     Additionally, sliding doors tend to be larger than most windows, therefore, they tend to become “loose” over time through repeated use. As such doors require tight interfitting between parts in order to provide a strong moisture barrier, such loosening tends to degrade the moisture barrier capabilities of the door. 
     Therefore, there exists a need in the art for a sliding door system that has moisture barrier capabilities that overcome the above stated problems found in the art. Specifically, such a door must provide a high level of reliability in its moisture barrier properties while maintaining a sufficiently small lower threshold that addresses user comfort and complies with the Americans with Disabilities Act. Such a door must maintain the high level of moisture barrier reliability even if the door becomes loose through normal wear and tear and the passage of time. The threshold found on such a door should be relatively more comfortable to walk across with respect to current sliding door systems and must be relatively easy to bypass in a wheelchair. Ideally, such a door will be of relatively simple design and construction using standard manufacturing techniques to construct and will be relatively easy to use and maintain. 
     SUMMARY OF THE INVENTION 
     The sliding door assembly of the present invention addresses the aforementioned needs in the art. The sliding door assembly provides a a moisture barrier that has a high level of reliability. The sliding door assembly uses a small lower threshold that addresses user comfort and complies with the Americans with Disabilities Act. The flanging system on the threshold is relatively more comfortable to walk across with respect to current sliding door systems and is relatively easy to bypass in a wheelchair. The sliding door assembly maintains the high level of moisture barrier reliability even after the door becomes loose through normal wear and tear and the passage of time. The sliding door assembly is of relatively simple design and construction using standard manufacturing techniques and is relatively easy to use and maintain. 
     The sliding door assembly of the present invention is comprised of a frame that has a top leg and a bottom leg joined by a first side leg and a second side leg such that a first channel is located along a portion of the top leg, the first channel having a curved portion. A pocket extends along a portion of the top leg, the first side, a portion of the bottom leg, and between the top leg and the bottom leg, along a mullion. A compression gasket is located within the pocket, the gasket being continuous in order to form a closed loop. A first jamb extends along the first side leg, the first jamb having a first angled face, a first opening located on the first angled face, and a first inner wall. A first sash has a second jamb with a second angled face located along a first side edge of the first sash. The first sash also has an inner face and an outer face. A post, having a roller, is attached to a top edge of the first sash and passes through the first channel such that the roller rests on the top leg in order to gravitationally suspend the first sash therefrom and permit the first sash to slide along the top leg. A first dog is rotatably attached to the first side edge of the first sash. A third jamb extends along the mullion, the third jamb having a third angled face, a second opening located on the third angled face, and a second inner wall. The first sash has a fourth jamb with a fourth angled face located along a second side edge of the first sash opposite the first side edge. A second dog is also rotatably attached to the second side edge of the first sash. A handle is attached to the first sash and is operatively connected to the first dog and the second for rotation of the two dogs. A second sash is fixedly attached to the frame and to the mullion. The first sash is slidable between an open position and a closed position wherein when the first sash is in a closed position, the first angled face faces the second angled face in close proximity and the third angled face faces the fourth angled-face in close proximity. The handle is activated in order to rotate the first dog and the second dog so that the first dog passes through the first opening and acts on the first inner wall and the second dog passes through the second opening and acts on the second inner wall so that the inner face of the first sash presses against the gasket in order to achieve an airtight seal between the first sash and the gasket. The bottom leg has a second channel and the first sash has a pin that passes through the second channel, the pin helping to stabilize the first sash during first sash movement. The handle can be latched, which may be an over-center latch, in order to maintain the dogs in the acting relationship with their respective inner walls. Ramped detents located on the top leg help hold the first sash in a fully closed or a fully open position. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of the sliding door assembly of the present invention in an open position. 
     FIG. 2 is a perspective view of the sliding door assembly of the present invention in a closed position. 
     FIG. 3A is a sectioned view, taken along line  3 A-C in FIG. 2, showing the door in a closed and locked position. 
     FIG. 3B is a sectioned view, taken along line  3 A-C in FIG. 2, showing the door in a closed and unlocked position. 
     FIG. 3C is a sectioned view, taken along line  3 A-C in FIG. 2, showing the door in an open position. 
     FIG. 4A is a sectioned view, taken along line  4 A-C in FIG. 2, showing the door in a closed and locked position. 
     FIG. 4B is a sectioned view, taken along line  4 A-C in FIG. 2, showing the door in a closed and unlocked position. 
     FIG. 4C is a sectioned view, taken along line  4 A-C in FIG. 2, showing the door in an open position. 
     FIG. 5 is a perspective view of the operable sash illustrating the range of motion of the sash. 
     FIG. 6 is an exploded view of the sliding door assembly. 
     FIG. 7 is a close-up view of the top side edge of the sash. 
     FIG. 8 is an exploded view of the roller assembly. 
    
    
     Similar reference numerals refer to similar parts throughout the several views of the drawings. 
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to the drawings, it is seen that the sliding door assembly of the present invention, generally denoted by reference numeral  10 , is comprised of a first sash  12  that slides within a frame  14  and a second sash  16  that is fixed to the frame  14  and to a mullion  18  described below. Each sash  12  and  16  may have appropriate glazing  20  therein as desired. 
     As seen, the frame  14 , which may be generally rectangular has a top leg  22 , a bottom leg  24 , a first side  26  joining the top leg  22  and the bottom leg  24  and a second side  28  also joining the top leg  22  and the bottom leg  24 . The mullion  18  extends between the top leg  22  and the bottom leg  24 , which mullion  18  is generally parallel with the two side legs  26  and  28  and positioned between the side legs  26  and  28 . The top leg  22  has at least one channel  30  located thereon below the nailing fin  32 . Each channel  30  has a straight portion and a curved portion. The bottom leg  24  also has at least one channel  34  that also has a straight portion and a curved portion. Advantageously, although strictly not necessarily, each bottom channel  34  is coextensive with a respective one of the top channel  30  and vice versa. At least one weep hole  36  is located below on the bottom leg  24  so that any moisture that enters the second channel  34  is expelled through the weep hole  36 . 
     A pocket  38  is located on the first side leg  26 , the portion of the top leg  22  that extends between the first side leg  26  and the mullion  18 , on the mullion  18 , and on the bottom leg  24  between the first leg  22  and the mullion  18  so that the pocket  38  is continuous. A compression gasket  40  is located within the pocket  38  and is also continuous and may be of single piece construction. A first jam  42  is located on the first side leg  26  such that the first jamb  42  has a first seating face  44 , a first angled face  46 , that is angled relative to the first seating face  44 , and a first inner wall  48  beyond the first angled face  46 . At least one first opening  50  is located on the first angled face  46  of the first jamb  42 . A second jamb  52  is located on the mullion  18 , the second jamb  52  having a second seating face  54 , a second angled face  56 , that is angled relative to the second seating face  54 , and a second inner wall  58  beyond the second angled face  56 . At least one second opening  60  is located on the second jamb  52  in order to allow access to the second inner wall  58 . 
     The first sash  12  has a top edge  62  and a bottom edge  64  joined by a first side edge  66  and a second side edge  68 . A post  70  is located on the top edge  62  of the first sash  12  and has a roller assembly  72  on the top thereof. As seen in FIG. 8, the roller assembly  72  is comprised of one or more rollers  74  that have an axial pin  76  that passes through an opening  78  located on the post  70 , the axial pin  76  having an appropriate clip  80  to retain the axial pin  76  within the opening  78 . The post  70  passes through the first channel  30  such that the rollers  74  sit on the top surface of the top leg  22  and roll thereon. This gravitationally suspends the first sash  12  from the frame  14 . The post  70  is able to rotate with respect to the first sash  12  in order to allow the roller assembly to turn with a corresponding change of direction of the first sash  12  when the post  70  enters the curved portion of the first channel  30  so that the post  70  and its roller assembly  72  can follow the curvature of the first channel  30 . The roller assembly can be clipped onto the top edge  62  of the first sash  12 . The first sash  12  can have more than one post  70  and roller assembly  72 , such as illustrated in FIGS. 1,  2 ,  5  and  6 , wherein the first sash  12  has a post  70  and roller assembly  72  proximate each corner of the first sash  12  with each post  70  passing through a respective first channel  30  of the top leg  22  of the frame  14 . If first sash  12  is particularly large or heavy, the first sash can have three or more posts  70  and roller assemblies  72  each cooperating with a respective first channel  30  on the top leg  22  of the frame  14 . Alternately, the roller assembly  72  can comprise multiple rollers  74  or roller pairs disposed serially along the post  70  (similar to the landing gear carriage of a jumbo jet) which roller assembly  72  can be attached to the first sash  12  by one or more posts  70 . 
     At least one pin  82  is attached to the bottom edge  64  of the first sash  12  such that the pin  82  passes through the second channel  34  located on the bottom leg  24  of the frame  14 . Advantageously, although not necessarily, each pin  82  is disposed generally directly below each post  70  located on the top edge  62  of the first sash  12 . The pin  82  rides in the second channel  34  during first sash  12  movement and, by having a diameter that is only slightly smaller than the width of the second channel  34 , helps maintain the stability of the first sash  12  during first sash  12  movement. 
     A third jamb  84  is located on the first side edge  66  of the first sash  12 , which third jamb  84  has a third seating face  86 , a third angled face  88 , and at least one third opening  90 , while a fourth jamb  92  is located on the second side edge  68  of the first sash  12 , which fourth jamb  92  has a fourth seating face  94 ,a fourth angled face  96 , and at least one fourth opening  98 . 
     Accordingly, the first sash  12  is able to slide within at least a portion of the frame  14  with the post  70  and roller assembly  72  suspending the first sash  12  from the top leg  22  of the frame  14  such that the roller assembly  72  facilitates the sliding of the first sash  12 . This permits the first sash  12  to slide between an open position (FIGS. 1,  3 C,  4 C, and  5 ) and a closed positioned (FIGS. 2,  3 A,  3 B,  4 A, and  4 B) with respect to the frame  14 . 
     In order to slide the first sash  12  from the open position to the closed position, the first sash  12  is moved appropriately. As the first sash  12  nears closing, the post  70  enters the curved portion of the first channel  30  of the top leg  22  of the frame  14  (and correspondingly, the pin  82  enters the curved portion of the second channel of the bottom leg  24  of the frame  14 ) causing the first sash  12  to change direction from is lateral movement with respect to the frame  14  and move toward the gasket  40  in following the curvature of the first channel  30  of the top leg  22 . When the first sash  12  is fully closed, the third jamb  84  seats on the first jamb  42  such that the third seating face  86  of the third jamb  84  is seated on the first seating face  44  of the first jamb  42  and the first angled face  46  of the first jamb  42  seats on the third angled face  88  of the third jamb  84 . Correspondingly, the second jamb  52  seats on the fourth jamb  92  such that the second seating face  54  of the second jamb  52  is seated on the fourth seating face  94  of the fourth jamb  92  and the second angled face  56  of the second jamb  52  seats on the fourth angled face  96  of the fourth jamb  92 . The inner face of the first sash  12  presses against the gasket  40  in order to create a seal. 
     In order to press the first sash  12  against the gasket  40  on the frame  14  a compression subsystem is used. The compression subsystem is comprised of at least one dog gear  100  that is rotatably attached to the first side edge  66  of the first sash  12  and to the second side edge  68  of the first sash  12 . A handle  102  is attached to the first sash  12  and is operatively connected to the dog gears  100 . More than one dog gear  100  may be located along the first side edge  66  of the first sash  12  and along the second side edge  68  of the first sash  12 . The handle  102  may be connected by a gear system (not illustrated) of any standard design that directly connects to each dog gear  100  or some or all of the dog gears  100  may be attached to a shaft  104  such that operation of the handle  102  causes the gear system to rotate the shaft  104  which in turn rotates the dog gears  100 . The handle  102  may have an appropriate lock subsystem, such as a bi-directional clutch or an over-center latch, in order to maintain the handle  102  in a given position. Specifically, when the first sash  12  is in the closed position, the handle  102  is rotated so as to rotate the dog gears  100  such each dog gear  100  in the right side edge  66  of the first sash  12  pass through a respective first opening  50  of the first jamb  42  and through a respective third opening  90  of the third jamb  84  and presses upon the first inner wall  48  of the first jamb  42 , while simultaneously, each dog gear  100  on the second side edge  68  of the first sash  12  passes through a respective second opening  60  of the second jamb  52  and through a respective fourth opening  98  of the fourth jamb  92  and presses upon the second inner wall  58  of the second jamb  52 . This causes the first sash  12  to be pressed onto the gasket  40  on the frame  14  thereby creating a seal. This also prevents the first sash  12  from moving, thereby effectively locking the door system  10 . The lock subsystem of the handle  102  maintains the dog gears  100  in this position. In order to move the first sash  12  into the open position, the handle  100  is counterrotated causing the dog gears  100  to rotate in reverse direction and thereby exiting their respective openings. This unlocks the first sash  12  and allows it to slide with respect to the frame  14 . 
     A first detent  106  is located on the top leg  22  proximate the curved portion of the first channel  30  while a second detent  108  is located on the top leg  22  proximate the opposite side of the first channel  30  relative to the side with the first detent  106 . When the first sash  12  is slid into the closed position, the roller  74  rolls into the first detent  106  with this detent  106  helping to hold the sash  12  in the closed position without having to lock the sash  12  closed. The first detent  106  maintains the roller  74  within the detent  106  thereby helping prevent the sash  12  from sliding back into an opened position. The first detent  106  is ramped so that when a person is sliding the sash  12  into the closed position, the roller  74  gradually rolls into the first detent  106  avoiding the sash  12  from being slammed closed. Additionally, when the sash  12  is being slid open, the ramped nature of the first detent  106  helps the person opening the sash  12  to be able to gradually and easily roll the roller  74  out of the detent  106  and place the sash  12  into an open position. In similar fashion, when the first sash  12  is slid into a fully open position, the roller  74  rolls into the second detent  108  with this detent  108  helping to hold the sash  12  in the open position. The second detent  108  maintains the roller  74  within the detent  108  thereby helping prevent the sash  12  from sliding back into a partially open position. The second detent  108  is also ramped so that when a person is sliding the sash  12  into the fully open position, the roller  74  gradually rolls into the second detent  108  avoiding the sash  12  from being slammed open. Additionally, when the sash  12  is being slid back toward a closed position, the ramped nature of the second detent  108  helps the person performing this task to be able to gradually and easily roll the roller  74  out of the second detent  108 . 
     While the invention has been particularly shown and described with reference to an embodiment thereof, it will be appreciated by those skilled in the art that various changes in form and detail may be made without departing from the spirit and scope of the invention.

Summary:
A sliding door has a sash suspended from a top leg of a frame by having a curved channel extend along this leg and providing the sash with a post that passes through the channel and a roller attached to the post, such that the roller sits on the leg and permits the sash to slide relative to the frame. In closing the door, the sash moves towards the inner portion of the frame and is pressed against a compression gasket that extends about the inner portion of the door in order provide an airtight seal between the sash and the frame. A handle is operatively connected to a dog that is attached to the frame which dog acts on an inner wall of a jamb on the frame in order to maintain the seal.