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You are an expert at summarizing long articles. Proceed to summarize the following text: 
FIELD OF THE INVENTION 
       [0001]    This invention relates to windows and doors, trim assemblies for windows and doors, and related processes for trimming a window or door. 
       BACKGROUND OF THE INVENTION 
       [0002]    In both new building construction and during renovations, remodeling or other reconstruction activities involving replacement of a building window, it is often desirable to provide the window with an exterior trim that conceals a gap between interfacing edges of the window and the exterior siding or other finish material used to protect the building against the affects of weather and/or to provide a desired ornamental effect. Exterior window trimming has generally involved the use of several individual components that are separately fastened to the building wall and/or the window. 
         [0003]    U.S. Pat. No. 4,193,238 discloses a snap-on exterior cover or trim system for window casings. The system includes a plurality of case molding members adapted to be disposed around the window opening in engagement with each other, a plurality of brackets securable to a window casing, and fastening means for each bracket. In an illustrated embodiment, eight individual brackets are separately fastened to the window casing with screws. The bracket includes a base with a slotted opening, and a helical spring is disposed over the screw between the base and the head of the screw to allow adjustable repositioning of the brackets as needed for installation. The plurality of case molding members are adapted to be attached to the brackets using a snap-on or interference connection. 
       SUMMARY OF THE INVENTION 
       [0004]    In accordance with an aspect of the invention, a window or door and trim assembly that allows easy and secure attachment of an exterior window or door trim to a window frame is provided. The assembly includes a window or door having a casing or frame that defines a clip receiving groove, a plurality of resilient clips receivable in a clip receiving groove, and a pre-assembled trim cover retainable on the window or door casing or frame by snap-on attachment of the trim cover to the resilient clips. 
         [0005]    In accordance with another aspect of the invention, a method of installing an exterior trim assembly to a window or door casing or frame is provided. The method includes steps of providing a window or door casing or frame defining clip receiving grooves, inserting resilient clips into the clip receiving grooves, and attaching a pre-assembled trim cover to the window or door casing or frame employing a snap-on connection between the pre-assembled trim cover and the resilient clips. 
         [0006]    These and other features, advantages and objects of the present invention will be further understood and appreciated by those skilled in the art by reference to the following specification, claims and appended drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]      FIG. 1  is a perspective view of a window and exterior trim assembly in accordance with an illustrated embodiment of the invention. 
           [0008]      FIG. 2  is a transverse cross-sectional view or profile of a resilient clip used for holding an exterior trim cover to a window unit in accordance with an illustrated embodiment of the invention. 
           [0009]      FIG. 3  is a schematic horizontal cross-sectional view of a completed assembly as illustrated in  FIG. 1 . 
           [0010]      FIG. 4  is an enlarged schematic horizontal cross-sectional view showing details of the connection between the resilient clip, the window unit, and the exterior trim cover. 
       
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0011]    A window and exterior trim assembly  10  in accordance with the invention is shown in  FIG. 1 . The assembly includes a window unit  12 , a plurality of resilient clips  13 , and a one-piece, pre-assembled exterior trim cover  16 . In the illustrated embodiment, window unit  12  is a double-hung window of generally conventional design except for the inclusion of clip receiving grooves  18  defined in the various frame members that support upper sash frame  20  and lower sash frame  22  for upward and downward movement. Sash frames  20  and  22  frame and retain upper window pane  24  and lower window pane  26 , respectively. While the illustrated embodiment is a double-hung window, window unit  12  may be generally any type of window that forms single or multiple window panes (e.g., glass, plastic or other light transmissive sheet-like material), whether openable, pivotable, slideable or stationary (not openable), including roof windows or skylights, as well as doors. 
         [0012]    In the illustrated embodiment, window unit  12  includes nailing fins  28  that extend outwardly from opposite sides of the window frame and from the top and bottom of the window frame to facilitate nailing, screwing, or tacking of the fins to wood studs or other building structure to facilitate proper positioning and orientation of the window in a building opening. However, as is conventional in the art, the various frame members, including side members or jambs  30 , top member or header  32 , and bottom member or sill  34  may subsequently be securely attached to wood studs or other building structure to secure window unit  12  in a building opening. In order to facilitate nailing, screwing or tacking of nailing fins  28  to a building structure, nailing fins  28  may be provided with preformed fastener apertures  36 . 
         [0013]    The various frame components employed in window unit  12  may be made of any suitable material, including wood, metal, (e.g., aluminum), metal clad framing (e.g., aluminum clad wood material), etc. 
         [0014]    Resilient clips  13  are configured to be securely retained in a clip receiving groove  18 , by manually inserting a portion of clip  13  into groove  18 . Clips  13  are also configured to cooperate with complementary features defined on exterior trim cover  16  to securely hold exterior trim cover  16  on widow unit  12  when exterior trim cover  16  is properly aligned with window unit  12  and pushed into engagement with clips  13  received in grooves  18  of window unit  12 . Resilient clips  13  are also configured and made of a material that allows easy deformation of certain features of the clip with respect to other features of the clip during the process of attaching the exterior trim cover  16  to the window unit  12 , and subsequent resilient recovery to its original form after full attachment of cover  16  to window unit  12 , whereby an interference connection or snap-on connection is employed to securely hold exterior trim cover  16  on window unit  12  via resilient clips  13 . 
         [0015]    A transverse cross section or profile of a resilient clip  13  in accordance with the illustrated embodiment of the invention is shown in  FIG. 2 . In profile, clip  13  has a generally V-shaped configuration in which an inner leg  38  is connected to an outer leg  39  at vertex  40 . Legs  38  and  39  are able to flex with respect to each other around vertex  40  when compressive forces are applied to legs  38  and  39 . However, when the force is removed, clip  13  exhibits sufficient resilience to return to its original form. Various resiliently deformable plastic and metal materials may be employed for making clip  13 . In general, extruded plastics are preferred, with extruded polyvinyl chloride clips being particularly preferred for their suitability and economy. Illustrated clip  13  also includes a generally L-shaped foot  42  that extends from an end of leg  38  opposite vertex  40 . More specifically, foot  42  extends approximately at a right angle away from the inner side (side closest the window pane after installation is complete) of inner leg  38  and then generally at a right angle parallel to and spaced from the inner side of inner leg  38  to define a channel or groove  44  between inner foot  42  and inner leg  38 . At the distal end of inner foot  42 , there is provided a barb  46  having a pointed end facing toward the inner side of inner leg  38 . At an end of outer leg  39  opposite vertex  40 , an outer foot  48  extends outwardly at an acute angle from the outer side of outer leg  39 . 
         [0016]      FIG. 3  shows a schematic horizontal cross section of the illustrated assembly shown in  FIG. 1 . When the assembly is completed, inner foot  42  is retained in groove  18 , and exterior trim cover  16  is held in place by outer feet  48  engaging a retainment landing feature  50  defined on exterior trim cover  16  along each of the side members  51  and  52 , and along the top member  54 . Similar features may be provided along bottom member  55 , and a resilient clip  13  may be used for connecting a clip  13  in groove  18  of sill  34  and to bottom member  55  of exterior trim cover  16 . However, in the illustrated embodiment only five clips  13  are used and illustrated, including two at each side, and one along the top of window unit  12 . In some cases it may be possible to use as few as two clips  13  (one on each side). 
         [0017]    An enlarged schematic cross-sectional view illustrating details of the connection between resilient clip  13  and window unit  12 , and between resilient clip  13  and exterior trim cover  16  is shown in  FIG. 4 . Groove  18  in window unit  12  includes kerfs or serrations  58  and  59  that engage inner foot  42  to securely retain foot  42  in groove  18 , with engagement of barb  46  on inner foot  42  with a serration  58  providing secure attachment of clip  13  to a window unit  12 . 
         [0018]    In accordance with certain aspects of this invention, exterior trim cover  16  is preferably provided in the form of a pre-assembled, one-piece unit in which members  51 ,  52 ,  54  and  55  are connected together as shown in  FIG. 1 . Such connection can be achieved with fasteners, such as screws, nails, bolts, rivets or the like, adhesives, welding, or any other suitable means, which may depend on the material used for making the components of the exterior trim cover  16 . Preferably, for reasons of efficiency and economy, members  51 ,  52 ,  54  and  55  are extruded metal or plastic, with extruded aluminum being a particularly preferred alternative. However, it is conceivable that the entire exterior trim cover  16  can be formed as a single unit, such as in an injection molding process. 
         [0019]    In accordance with various aspects of the invention, there is provided a quick and simple technique or method for installing an exterior trim on a window unit. The method involves using a window unit, resilient clips, and an exterior trim cover as generally described herein. In the illustrated embodiment, after window unit  12  has been installed in a building opening employing generally conventional techniques, clips  13  are inserted at various locations into grooves defined along a front exterior face of window unit  12 . In the illustrated example, the installer need merely insert an inner foot  32  of each of five clips  13  into grooves  18  as generally indicated in  FIG. 1 , with the foot being fully inserted as illustrated in  FIG. 4 . Thereafter, a pre-assembled exterior trim cover is aligned with the window unit  12  and pushed into engagement with clips  13  so that outer feet  48  engage landings  50 , at least along opposite sides of the window unit, whereby an interference connection is achieved. 
         [0020]    The above description is considered that of the preferred embodiments only. Modifications of the invention will occur to those skilled in the art and to those who make or use the invention. Therefore, it is understood that the embodiments shown in the drawings and described above are merely for illustrative purposes and not intended to limit the scope of the invention, which is defined by the following claims as interpreted according to the principles of patent law, including the doctrine of equivalents.

Summary:
An improved window and trim assembly that facilitates quick and easy installation of a trim assembly on a window includes a window or door unit having a casing that defines a plurality of clip receiving grooves, a plurality of resilient clips receivable in the clip receiving grooves, and a pre-assembled trim cover retained on the window or door unit by the resilient clips. Attachment of the exterior trim cover to the window or door unit involves inserting clips into the grooves and pushing the cover onto the window or door unit until features on the trim cover engage the clips.