You are an expert at summarizing long articles. Proceed to summarize the following text:

You are an expert at summarizing long articles. Proceed to summarize the following text: 
CROSS REFERENCE TO RELATED APPLICATIONS:  
       [0001]     The priority benefit of U.S. provisional application Ser. No. 60/563,390 filed Apr. 19, 2004 is claimed. 
     
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT  
       [0002]     Not Applicable.  
       REFERENCE TO A SEQUENCE LISTING, A TABLE, OR A COMPUTER PROGRAM LISTING COMPACT DISK APPENDIX  
       [0003]     Not Applicable.  
       BACKGROUND OF THE INVENTION  
       [0004]     The present invention relates to sliding screen doors.  
         [0005]     Sliding doors are common in more contemporary homes. Many of these doors are multi-element doors and include a screen door which is simply a screens mounted to a sliding frame, typically a metal frame and most commonly, an aluminum frame. The size of these doors varies considerably, each manufacturer having its own range of sizes. Accordingly, when sliding doors need to be replaced, the size of the replacement door is a concern. Most manufacturers of after-market sliding doors provide some mechanism for adjusting the height of their replacement door at the time of installation.  
         [0006]     Plastics are being used with increasing frequency as replacements for wood and metal and even ceramic materials. In construction, plastic piping has replaced some metal and ceramic piping. Vinyl shutters have replaced wood and aluminum shutters. Foamed plastic, particularly foamed vinyl, has found uses in molding and screen doors. Foamed vinyl is especially attractive as a substitute for wood because it can be trimmed with ordinary wood-working tools and techniques.  
         [0007]     There are problems with foamed vinyl, of course, particularly when used on the exterior of a residence or office building where it is exposed to the sun. Heat from the sun tends to cause it to expand, only to contract when the sun sets. Repeated cycles of expansion and contraction may result eventually in deformation  
         [0008]     Sliding doors are actually misnamed. While they appear to slide, they actually have small diameter wheels at the top and bottom that roll on tracks installed on the framing at the top and bottom of the opening they close. The tracks have low relief, perhaps a quarter inch at most. Thus, the fit of the door must be fairly precise so that these small wheels ride comfortably on these short tracks. A door that cannot be easily made to fit or that deforms over time would obviously not be suitable for such a purpose  
         [0009]     Nevertheless, there remains a need for replacement sliding screen doors that are easily adjusted to the size needed and remain dimensionally stable over time.  
       SUMMARY OF THE INVENTION  
       [0010]     The present invention is a sliding screen door having a frame made of plastic, preferably foamed plastic. The top and bottom rails (which are horizontal members) of the doorframe are easily trimmed using standard woodworking tools and techniques. The stiles (which are vertical members) of the doorframe may be reinforced so that they do not appreciably deform during the life of the door.  
         [0011]     A feature of the present invention is the use of foamed plastic, with foamed vinyl preferred. Foamed vinyl is durable, requires no painting, is easily washable, and is lightweight and relatively inexpensive compared to aluminum and many types of wood.  
         [0012]     Another feature of the present invention is the simplicity with which the sliding screen door can be adjusted to fit the framed opening at the job site. The top rail can be trimmed quickly, easily and precisely with a circular saw for example to the height required.  
         [0013]     Still another feature of the present invention is the combination of reinforcing to the stiles in order to reduce deformation and add strength to a sliding screen door of foamed vinyl, so that the door operates smoothly on the sliding door tracks. The door is also light-weight so that it is easy to slide.  
         [0014]     Other features and their advantages will become readily apparent to those skilled in the art of construction materials from a careful reading of the Detailed Description of Preferred Embodiments, accompanied by the drawings.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0015]     In the drawings,  
         [0016]      FIG. 1  is a perspective view of a corner of a sliding screen door, according to a preferred embodiment of the present invention;  
         [0017]      FIG. 2  is a perspective view of a corner of the sliding screen door of  FIG. 1 , according to a preferred embodiment of the present invention;  
         [0018]      FIG. 3  is a perspective view of a corner of an alternate sliding screen door, according to a preferred embodiment of the present invention;  
         [0019]      FIG. 4  is a perspective view of a corner of the sliding screen door of  FIG. 3 , according to a preferred embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0020]     The present invention is a sliding screen door having a frame made of plastic, preferably foamed plastic, and most preferably of foamed vinyl. Other materials may be added, such as wood flour and coloring agents, provided that they do not significantly alter the ability of the user to trim the screen door using wood-working tools and techniques.  
         [0021]     Additionally, in a preferred embodiment, stiffening is added to the stiles and potentially also to the rails of the present screen doorframe, in order to reduce deformation that might otherwise result from exposure to heat. Stiffening added to stiles, which, being the long, vertical elements of the sliding doorframe, are the most susceptible to heat-related deformation, will have no impact on the ability of the user to trim the rails to fit, provided that the rails run the full width of the door and the stiles do not run the full height. Moreover, stiffening added to the rails, especially if confined to the lower portion of the top rail, will have only a minor impact on the ability of the user to trim the door to fit; that is, it will limit the extend to which the upper rail can be trimmed.  
         [0022]     Referring now to the figures,  FIGS. 1 and 2  show a first embodiment of the present invention, namely the corner of a sliding screen door made according to a preferred embodiment of the present invention. The corner shown, namely the top right corner, is typical of the other four comers (top left, bottom left, and bottom right). In particular, the door, generally indicated by reference number  10 , includes a top rail  12  and an opposing bottom rail (not shown but symmetric with top rail  12 ) and a right stile  14  and an opposing left stile (not shown) that are joined at  16  to form a generally rectangular frame that defines an opening  18 . Opening  18  is covered with screen material  20  fitted into a spline groove  22  and held in place with a spline  24 .  
         [0023]     Across top rail  12  is a header  30  formed with two legs  32  and  34  that straddle top rail  12  and arms  36  and  38  that serve to hold in alignment plural wheels  40  (one shown) with their axes horizontal so that they can ride a track (not shown) at the top and bottom of an opening, allowing door  10  to slide freely to the left and right. Wheels  40  are held between arms  36  and  38 , by leaf springs  42  attached to header  30  and a yoke  44  that holds wheel  40 . Wheels on bottom rails are held rigidly, as is well known in the prior art.  
         [0024]     Header  30  is held to top rail  12  by screws  50  and  52  that extend through slots  54  and  56  formed in header  30 . For major adjustments, screws  50  and  52  are removed and header  30  is slid off top rail  12 . A portion of top rail  12  is trimmed away using, for example, a circular saw to remove a portion of top rail  12  and thereby shorten door  10 . The header  30  is repositioned on top rail  12  and fastened with screws  50 ,  52 . If fine adjustments in the location of header  30  are required, screws  50 ,  52  can be loosened and header moved slightly up or down as required. Then screws  50 ,  52 , are retightened.  
         [0025]     Referring now to  FIGS. 3 and 4 , there is shown a perspective view of a top right corner of an alternative embodiment of the present sliding screen door  60 . Screen door  60  is symmetric left to right and top to bottom so that the top right corner is representative of the top left corner, the bottom left corner and the bottom right corner. Screen door  60  has a top rail  62  and an opposing bottom rail (not shown), a right stile  64  and an opposing left stile (not shown). The rails and stiles are joined together to form a rectangular frame that defines an opening  68 . Screen material  70  is used to cover opening  68  and fastened to door  60  by forcing it into a spline groove  72  with a spline  74 .  
         [0026]     Instead of a header  30 , in the embodiment shown in  FIGS. 3 and 4 , a deep groove  80  is milled in top rail  62  thereby defining members  86 ,  88 , and wheels  90  (one shown) are mounted within groove  80 , and held to members  86 ,  88 , by leaf springs  90  (one shown) held within a yoke  94 , in the same manner they are mounted between arms  36  and  38 , namely, biased upwards by a leaf spring  42  attached to the bottom of groove  80  by a screw.  
         [0027]     When screen door  60  must be trimmed to reduce its height, springs  90  are removed along with wheels  90 . Then top rail  62  is cut using, for example, a circular saw to reduce the height of top rail  62 . Groove  80 , however, is deep enough so that even after removing a significant portion of top rail  62 , groove  80  is still sufficiently deep so that it can accommodate wheels  90 . Springs  92  are either bent to match the new depth of groove  80  or replaced with different springs  92  and refastened with screws to the bottom of groove  80 .  
         [0028]     The present screen door  10 ,  60 , is designed to make it a simple matter to replace screen material  20 ,  70  by removing spline  24 ,  74 , from spline groove  22 ,  74 . New screen material  20 ,  70 , can then be placed over opening  18 ,  68  and its edges reinserted into spline groove  22 ,  72 , by pressing spline  24 ,  74 , into groove  22 ,  72  over screen material  20 ,  70 .  
         [0029]     Stiles  14 ,  64 , and rails  12 ,  62 , can be made of solid plastic, hollow plastic, or foamed plastic, preferably vinyl, and they may be filled plastic, using for example, wood flour, or other materials to give it desirable properties or reduce costs, provided that the basic requirement of making top rail  12 ,  62  trimmable using standard woodworking tools and techniques is not compromised. Stiles  14 ,  64  may be made stiffer using metal bars inserts such as rods, tube, bars, or angled pieces around which the plastic is extruded. Other stiffening techniques may also be used.  
         [0030]     It will be readily apparent that many substitutions and modifications can be made to the foregoing preferred embodiments without departing from the spirit and scope of the present invention, defined by the appended claim.

Summary:
A sliding plastic screen door made of foamed vinyl can be trimmed at the job site to fit the door it will occupy. The door may have reinforcing in its styles and potentially also in its rails but not in the top portion of the rail, which is where it may be cut to fit. Two embodiments are disclosed, one with a header that can be removed prior to trimming the top rail, and the other with a deep slot for the rollers, which top rail can be trimmed directly and the wheels reattached.