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CROSS REFERENCE TO RELATED APPLICATIONS  
         [0001]    This application claims priority to European Application No. 02077975.7, filed Jul. 22, 2002, which is hereby incorporated by reference as if fully disclosed herein.  
         BACKGROUND OF THE INVENTION  
         [0002]    1. Field of the Invention  
           [0003]    This invention relates to a hollow rail or bar for a fabric covering for an architectural opening, such as a bottom rail for a fabric roller blind or a top or bottom rail for a roman shade, and a method for attaching the fabric of the covering to the rail.  
           [0004]    2. Description of the Relevant Art  
           [0005]    Profiles for elongate hollow bottom rails for fabric window coverings are known, for example, from: GB 1,191,532, GB 1,366,961, GB 1,462,613 and JP 63-24786. Often, such bottom rails are cut from a length of hollow, extruded plastic or hollow, roll formed or extruded metal and are of round, elliptical or generally pear shaped cross-section. The interior of such a bottom rail often has had a continuous intermediate widthwise cross web, extending between the rail&#39;s walls on its opposite widthwise sides and dividing the inside of the rail&#39;s profile into upper and lower portions extending along the length of the rail. The upper portion has usually had a lengthwise opening or slot in the top of the rail, and in some window coverings, the lower portion has also had a lengthwise opening in the bottom of the rail. A marginal end of the fabric of a window covering has generally been inserted in such a lengthwise opening in a bottom rail to attach the fabric and rail together.  
           [0006]    One method of attaching a fabric to such a rail has involved providing the marginal end of the fabric with a stiffening (e.g., stiff plastic) member that extends along the length of the rail. The marginal end of the fabric with the stiffening member has been inserted into an end of the rail, above or below the rail&#39;s cross web, and then slid lengthwise along the cross web as the remainder of the fabric, extending through the rail&#39;s upper or lower lengthwise opening, is slid along the rail&#39;s lengthwise opening. The stiffening member has held the marginal end of the fabric within the upper or lower portion of the rail, into which the stiffening member has been inserted, and prevented the marginal end of the fabric from subsequently being pulled out of the rail, through its adjacent lengthwise opening in the rail&#39;s upper or lower portion. In a rail where the width of the stiffening member has been smaller than the width of the adjacent lengthwise opening in the rail&#39;s upper or lower portion, the interior of the upper and/or lower portion has been provided with a lengthwise locking shoulder, which can engage the stiffening member to prevent it from being pulled out of the adjacent lengthwise opening.  
           [0007]    Another method for attaching the fabric and rail, as described in U.S. Pat. No. 3,018,824, has involved providing clips within a lengthwise opening or groove in the rail&#39;s upper or lower portion. In this method, a creasing device has been used for inserting the fabric into the lengthwise opening and a clip driver has been used for subsequently inserting locking clips into the opening. The creasing device has used an elongated blade to push the fabric into the opening in a single operation. The clip driver has used a wheel to push the fabric into the opening as the wheel is rolled along the length of the opening.  
           [0008]    Yet another method for attaching a screen fabric to each side of a frame, as described in U.S. Pat. No. 5,127,143, has providing a spline in a shallow lengthwise groove in each side of the frame. In this method, a wheel has been rolled over both the screen fabric and the spline, lain atop the groove, to insert the screen fabric and spline into the groove.  
         SUMMARY OF THE INVENTION  
         [0009]    In accordance with this invention, an elongate hollow rail for a fabric covering for an architectural opening, such as a bottom rail for a fabric roller blind, is provided, having an upper portion with a lengthwise upper opening in the top of the rail and being characterized by:  
           [0010]    a pair of lengthwise upper locking shoulders in the interior of the upper portion on walls on opposite widthwise sides of the upper opening; and/or  
           [0011]    the upper locking shoulders being wedge-shaped and pointing inwardly of the upper portion and away from the upper opening; and/or  
           [0012]    the wall on a first widthwise side of the bottom rail extending above the wall on the opposite second widthwise side of the bottom rail about the opening.  
           [0013]    The rail can also have a lower portion with a lengthwise lower opening in the bottom of the rail and be characterized by:  
           [0014]    a pair of lengthwise lower locking shoulders in the interior of the lower portion on walls on opposite widthwise sides of the lower opening; and/or  
           [0015]    the lower locking shoulders being wedge-shaped and pointing inwardly of the lower portion and away from the lower opening; and/or  
           [0016]    the wall on the second widthwise side of the bottom rail extending below the wall on the first widthwise side of the bottom rail about the lower opening.  
           [0017]    The rail can further have a continuous intermediate widthwise cross web, dividing the interior of the rail&#39;s profile into upper and lower portions and be characterized by:  
           [0018]    the cross web being tilted widthwise; and  
           [0019]    opposite widthwise sides of the cross web being parallel but not coplanar.  
           [0020]    Also in accordance with this invention, a method is provided for attaching a fabric to a locking shoulder within an elongate hollow rail for a fabric covering for an architectural opening having a lengthwise upper opening in the top of the rail, by the steps of:  
           [0021]    securing the rail to a stationary support structure with its lengthwise upper opening facing upwards;  
           [0022]    overlaying the rail and its upper opening and walls with a fabric having a stiff straight marginal edge, so that the stiff marginal edge lies parallel and adjacent to a wall on a widthwise side of the rail and the remainder of the fabric extends widthwise away from the stiff marginal edge and the rail and its other wall;  
           [0023]    pushing the fabric into the upper opening by rolling the circumferential edge of a fabric inserting wheel against the top of the fabric and lengthwise along, and inwardly of, the upper opening while allowing the stiff marginal edge to move widthwise towards the upper opening but preventing the remainder of the fabric from moving widthwise towards the upper opening; and then  
           [0024]    pushing the stiff marginal edge into the upper opening so that the stiff marginal edge engages the locking shoulder by again rolling the circumferential edge of the fabric inserting wheel against the top of the fabric and lengthwise along, and inwardly of, the upper opening while preventing the remainder of the fabric from moving widthwise towards the upper opening.  
           [0025]    This method is quick, efficient, and easy to use, and can be readily automated, particularly with the elongate hollow rail of this invention.  
           [0026]    The method can also be used to cover one wall of the rail with the fabric where the bottom of the rail has a lengthwise lower opening. This can be done by:  
           [0027]    rotating the rail in a direction such that the stiff marginal edge of the fabric is not disengaged from the locking shoulder and until the lengthwise lower opening faces upwards, the fabric covers the one wall and overlies the rail and its lower opening and the other wall, and the remainder of the fabric extends widthwise away from the rail and the other wall; and then  
           [0028]    pushing the fabric into the lower opening to form a first fold in the lower portion by rolling the circumferential edge of the fabric inserting wheel against the top of the fabric and lengthwise along, and inwardly of, the lower opening while allowing the remainder of the fabric to move widthwise towards the lower opening; and then  
           [0029]    inserting, in a lengthwise direction, a elongate first spline into the first fold.  
           [0030]    The method can also be used to cover the other wall of the rail with the fabric by:  
           [0031]    again rotating the rail in a direction such that the stiff marginal edge of the fabric is not disengaged from the locking shoulder and until its lengthwise upper opening faces upwards, the fabric covers the other wall and overlies the rail and its upper opening and the one wall, and the remainder of the fabric extends widthwise away from the rail and the one wall; and then  
           [0032]    pushing the fabric into the upper opening to form a second fold in the upper portion by rolling the circumferential edge of the fabric inserting wheel against the top of the fabric and lengthwise along, and inwardly of, the upper opening while allowing the remainder of the fabric to move widthwise towards the upper opening; and then  
           [0033]    inserting, in a lengthwise direction, a elongate second spline into the second fold.  
           [0034]    The method of this invention preferably involves repeatedly rolling the circumferential edge of the fabric inserting wheel along, and inwardly of, an opening in an upper or lower portion of the rail, especially repeatedly rolling the circumferential edge of the fabric inserting wheel in both lengthwise directions. The method can also involve attaching a roller blind or roman shade fabric to an upper opening of the rail and attaching a valance fabric to a bottom opening of the rail.  
           [0035]    Also in accordance with this invention, an apparatus is provided for attaching a fabric to an elongate hollow rail for a fabric covering for an architectural opening, comprising means for carrying out the steps of the method of the invention.  
           [0036]    Further aspects of the invention will be apparent from the detailed description below of particular embodiments and the drawing thereof. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0037]    [0037]FIG. 1A is a widthwise cross-section of a bottom rail (e.g., of a fabric roller blind) of this invention, showing the profile of the rail with only an upper lengthwise opening; a blind fabric is shown as being attached to an upper portion of the rail by only the stiff marginal edge of the fabric locked under a locking shoulder on a widthwise wall of the rail;  
         [0038]    [0038]FIG. 1B is a widthwise cross-section of the bottom rail of FIG. 1A; the fabric is shown as being secured to the upper portion of the rail by a spline, inserted after inserting the stiff marginal edge of the fabric and after covering the widthwise walls of the rail;  
         [0039]    FIGS.  2 - 4  are widthwise cross-sections of another bottom rail of this invention, showing its profile with upper and lower openings; a blind fabric is shown as being attached to an upper portion of the rail by a stiff marginal edge of the fabric locked under a locking shoulder on a widthwise wall of the rail; in some Figures, a valence fabric is attached to a lower portion of the rail by a stiff marginal edge of the valence fabric, locked under a locking shoulder on another widthwise wall of the rail; and  
         [0040]    FIGS.  5 - 7  show schematically various steps in the method of this invention for attaching one or more fabrics to a bottom rail as shown in FIGS.  1 - 4 . 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0041]    [0041]FIGS. 1A and 1B show the widthwise profile of an elongated bottom rail  1  of an otherwise conventional roller blind (not shown). The bottom rail  1  has a front wall  3  and a rear wall  4 , on opposite widthwise sides of the rail, and a closed bottom wall  5 . Within the bottom rail  1  is a lengthwise internal channel  6  which is divided into an upper portion  7  and a lower portion  9  by a continuous lengthwise cross web or cross member  11 . The cross web  11  is slanted downwardly widthwise from the rear wall  4  to the front Wall  3  and preferably includes a small vertically-extending dog-leg  13  in its middle, so that opposite widthwise sides of the cross web  11  are parallel but not coplanar. The reason for the cross web  11  being slanted is so that the rail  1  can be of minimum size but still have a sufficiently large upper portion  7  to hold securely a blind fabric F. However, the rail&#39;s closed bottom  5  makes the use of the cross web  11 , to hold the rail together, preferred but not necessary. Moreover, the cross web  11 , if used, need not be slanted if the rail  1  is made larger. Nevertheless, the use of internal strengthening ribs on the rail&#39;s walls  3 , 4  may well be desirable if the cross web is not used and/or the rail is made larger.  
         [0042]    The top  15  of the front wall  3  preferably extends over the top  17  of the rear wall  4 . This shields a lengthwise upper opening or slot  19 , in the top of the upper portion  7  between the two opposite walls  3 , 4  of the rail  1 , from view from the front wall  3 . The upper opening  19  extends lengthwise substantially the full length of the rail  1  and opens into the upper portion  7  of the channel  6 , so that the entire length of the blind fabric F can be inserted into the upper portion  7  of the rail through the upper opening  19 .  
         [0043]    Two fabric upper locking shoulders  21 ,  23  preferably extend lengthwise along the inner surface of the front wall  3  and rear wall  4 , respectively, in the upper portion  7  of the rail&#39;s channel  6  and are downwardly slanted widthwise towards the middle of the rail. Between these two upper locking shoulders  21 ,  23  is a gap  25  having a width that allows a widthwise straight stiff marginal edge portion  31  of the length of blind fabric F to be pushed, from the upper opening  19 , downwardly past the upper locking shoulders. Preferably, the upper locking shoulders are wedge-shaped and point inwardly of the upper portion  7  and away from the upper opening  19 .  
         [0044]    [0044]FIGS. 1A and 1B also show the marginal edge portion  31  of the blind fabric F inserted into the upper portion  7  of the rail  1 , so that the length of the fabric F extends lengthwise in the rail and the width of the marginal edge portion  31  is between the rear locking shoulder  23  and the cross web  11 . The marginal edge portion  31  of the fabric F is stiff but flexible and preferably resilient, but it is not rigid. The marginal edge portion  31  is preferably stiffened with a piece of plastic or the like  33 , bonded or sewn to the fabric, but can also be stiffened by treatment with a stiffening agent. The marginal edge portion  31  is also preferably slightly wider than the gap  25  between the two upper locking shoulders  21 ,  23 . Furthermore, the width of the marginal edge portion  31  is preferably somewhat greater than the width of the rear locking shoulder  23 . These features serve individually and collectively to help keep the marginal edge portion  31  below, and engaged by, one of the upper locking shoulders  21 , 23  (i.e., between the rear locking shoulder  23  and the cross web  11  in FIG. 1A) once the marginal edge portion  31  has been pushed downwardly past the upper locking shoulders. However, a single upper locking shoulder could also be used in the rail  1 , provided the widthwise gap between the one locking shoulder, on one wall of the rail, and the wall on the opposite widthwise side of the rail is smaller than the width of the stiff marginal edge portion  31  of the fabric, so that the marginal edge portion cannot be easily pulled out of the rail.  
         [0045]    The width of the stiff marginal edge portion  31  of the blind fabric F and of the gap  25  between the two upper locking shoulders  21 ,  23  is not considered critical, so long as the marginal edge portion  31  is somewhat wider than the gap  25 . In this regard, a width of about 3 to 9 mm, particularly about 6 mm, for the marginal edge portion  31  and a width of about 2.5 to 6 mm, particularly about 4 mm, for the gap  25  are preferred.  
         [0046]    [0046]FIG. 1B shows the same rail  1  and blind fabric F as FIG. 1A, but the fabric completely surrounds the rail and is held by its stiff marginal edge portion  31 , that is between the rear upper locking shoulder  23  and the cross web  11  and engages the underside of the rear upper locking shoulder  23 , and additionally by an upper lengthwise spline  35  below the upper front locking shoulder  21  (between the upper front locking shoulder and the cross web  11 ). The upper spline lies within an upper lengthwise fold  37  of the blind fabric F which is inserted into the upper portion  7  of the channel  6  through the upper opening  19  and downwardly past the gap  25  between the upper locking shoulders. The upper spline  35  locks against the fabric&#39;s stiff marginal edge portion  31  and the upper locking shoulders  21 , 23  beneath the upward facing opening  19 , to prevent the upper blind fabric fold  37  from being pulled out of the upper opening. For this reason, the upper spline  35  preferably has a cross-section which exceeds the width of the gap  25 , and the upper spline is. preferably inserted longitudinally into the upper blind fabric fold  37  from an open end of the rail (not shown).  
         [0047]    FIGS.  2 - 4  show another embodiment  101  of the rail of this invention, with like parts being referred to with like reference numerals greater by “100”. The rail  101  in FIGS.  2 - 4  has a front wall  103 , a rear wall  104 , lengthwise upper and lower portion  107 ,  109  of an inner channel  106  and a continuous lengthwise cross web  111  which substantially holds the front and rear walls together. The cross web  111  is slanted downwardly widthwise from the rear wall  104  to the front wall  103  and preferably includes a small vertically-extending dog-leg  113  in its middle The top  115  of the front wall  103  extends over the top  117  of the rear wall  104 , shielding the upper opening  119  from view. Instead of a bottom wall ( 5  in FIG. 1), at the bottom of the lower portion  109  of the rail  101  is a lower opening  127 . The bottom  128  of the rear wall  104  extends below the bottom  129  of front wall  103  to shield the lower opening  127  from view from the rear wall  104 .  
         [0048]    The rail  101  has two upper fabric locking shoulders  121 , 123  and two corresponding lower fabric locking shoulders  141 ,  143 . The lower locking shoulders  141 ,  143  extend lengthwise along the inner surface of the front wall  103  and rear wall  104 , respectively, in the lower portion  119  of the rail  101  and slant towards the middle of the rail. Between the two lower locking shoulders  141 ,  143  is a bottom gap  130  that corresponds to the gap  125  between the upper locking shoulders and has a width that allows a widthwise marginal edge portion  131  of the length of a blind fabric F to be pushed, from the lower opening  127 , downwardly past the lower locking shoulders. Preferably, the lower locking shoulders  141 ,  143  are wedge-shaped and point inwardly of the lower portion  109  and away from the lower opening  127 .  
         [0049]    As shown in FIG. 2A, a roller blind fabric F is attached to the upper portion  107  of the rail  101  and a valance fabric V attached to the lower portion  109  of the rail. The stiff marginal edge portion  131  of the blind fabric F, extending through the upper opening  119  of the rail  101 , is beneath the rear upper locking shoulder  123  (i.e., between the rear upper locking shoulder  123  and the cross web  111 ) and engages this shoulder. The gap  125  between the front and rear upper locking shoulders  121 , 123  and the width of the marginal edge portion  131  of the blind fabric F prevents the marginal edge portion  131  from being pulled vertically out of the rail through the upper opening  119 .  
         [0050]    The valance fabric V, extending through the lower opening  127  of the rail  101 , also has a stiff marginal edge portion  145  which is also locked above the front lower locking shoulder  141  (i.e., between the front lower locking shoulder and the cross web  111 ) and engages this shoulder. The gap  130  between the front and rear lower locking shoulders  141 , 143  and the width of the marginal edge portion  145  of the valance fabric V prevents the marginal edge portion  145  from being pulled vertically out of the rail through the lower opening  127 .  
         [0051]    As shown in FIG. 2B, the stiff marginal edge portion  131  of the blind fabric F is locked above the front lower locking shoulder  141  (between the front lower locking shoulder and the cross web  111 ) and covers the front wall  103 . A upper blind fabric fold  137 , containing a lengthwise upper spline  135 , is provided in the upper portion  107  of the rail&#39;s channel  106 , beneath the front upper locking shoulder  121  (between the front upper locking shoulder and the cross web  111 ). The upper spline  135  locks against the blind fabric&#39;s stiff marginal edge portion  131  and the upper locking shoulders  121 , 123 .  
         [0052]    The valance fabric V is similarly attached to the rail  1  by: locking its stiff marginal edge portion  145  beneath the rear upper locking shoulder  123  (between the rear upper locking shoulder and the cross web  111 ), and providing a lower valence fabric fold  147 , containing a lower lengthwise spline  149 , in the lower portion  109  of the channel  106 , above the rear lower locking shoulder  143  (between the rear lower locking shoulder and the cross web  111 ). The lower spline  149  locks against the valence fabric&#39;s stiff marginal edge portion  145  and the lower locking shoulders  141 , 143 .Thereby, the valance fabric V also covers the rear wall  104 .  
         [0053]    Since the rail  1  is preferably symmetrical, the fabrics F,V can also be attached the other way around, since it would have no visual effect.  
         [0054]    [0054]FIG. 3A shows the rail  101  with the blind fabric F attached as in FIG. 2B but with no valence fabric V.  
         [0055]    [0055]FIG. 3B shows the rail  101  with the blind fabric F attached without the use of a stiff marginal edge portion  131 . The blind fabric F is attached using only an upper lengthwise spline  135  and a lower lengthwise spline  149 . The upper spline  135  lies in an upper blind fabric fold  137  in the upper portion  107  of the rail&#39;s channel  106 , beneath the upper locking shoulders  121 , 123  (i.e., between the upper locking shoulders and the cross web  111 ). The lower spline  149  lies in a lower blind fabric fold  147 , in the lower portion  109  of the channel  106 , above the lower locking shoulders  141 , 143  (i.e., between the lower locking shoulders and the cross web  111 ). The top and bottom gaps  125 ,  130  are narrower than the two splines  135 , 149  and thus prevent the blind fabric from being pulled out of the rail  101 .  
         [0056]    [0056]FIG. 4 shows the rail  101 , with the blind fabric F attached to it and completely surrounding it as in FIG. 1B. In this regard, the stiff marginal edge portion  131  of the blind fabric F is locked below the rear upper locking shoulder  123  and an upper lengthwise spline  135  is provided in an upper blind fabric fold  137  in the upper portion  107  of the rail&#39;s channel  106 , beneath the front upper locking shoulder  121 . Preferably, a lower lengthwise spline (not shown) is also provided in a lower blind fabric fold  147  in the lower portion  109  of the channel  106 , above the lower locking shoulders  141 , 143 . After the blind fabric F is attached to the rail, the lower fold  147  in the blind fabric F is provided in the lower portion  109  of the channel  106 . Then, the stiff marginal edge portion  145  of the valance fabric V is inserted, through the bottom opening  127 , into the lower portion  109  and above the lower locking shoulders  141 , 143  (i.e., between the lower locking shoulders and the cross web  111 ) to hold the valance fabric V, as well as the blind fabric F, on the rail.  
         [0057]    A preferred method for attaching a blind fabric F or a valence fabric V to a rail of this invention is shown schematically in FIGS.  5 A- 5 D by reference to a fabric-rail assembly machine  201 . The five steps (1-5) of the method are as follows for making the product of, for example, FIG. 1B from the rail  101 :  
         [0058]    Step 1. FIG. 5A shows the rail  101  placed in a stationary rail holder  203  of the assembly machine  201 . The rail holder  203  preferably includes two longitudinally-extending holder blocks  203 A,  203 B which have either soft surfaces that contact the opposite sides of the rail&#39;s front and rear walls  104 , 105  or are shaped to mate with the opposite sides of the rail&#39;s front and rear walls. The holder blocks  203 A, 203 B can be brought together to grasp and hold the rail  101  between them and can subsequently be separated to release the rail. The holder blocks are adapted to grasp the rail with one of the rail&#39;s lengthwise openings  119  or  127  facing upwards and thus accessible from the top of the assembly machine.  
         [0059]    Step 2. FIG. 5A also shows the assembly machine  201  with the blind fabric F lain over the rail  101 , from one (e.g., left in FIGS.  5 - 7 ) widthwise side thereof (i.e., its front) to its other (e.g., right in FIGS.  5 - 7 ) widthwise side. As a result, the marginal edge portion  131  of the fabric is placed adjacent the rear wall  104  of the rail  101 , and the fabric&#39;s remainder  139  overlies the rail, its upward facing opening  119  or  127  and its front wall  103 .  
         [0060]    Step 3. If the fabric&#39;s marginal edge portion  131  is not already stiff, a stiffening strip of plastic or the like can be attached to it or a stiffening agent can be applied to it. In this regard, the stiffening strip can be self-adhesive or a layer of an adhesive can be applied to either the strip or the marginal edge portion  131  before adhering the two together.  
         [0061]    Step 4. As further shown in FIG. 5A, a conventional lengthwise retaining means  204  of the assembly machine  201 , on the one (left) widthwise side of the rail  101 , holds the remainder  139  of the fabric F against unwanted widthwise movement towards the rail&#39;s upward facing opening  119  or  127  and toward the other (right) widthwise side of the rail. Preferably, the fabric remainder  139  is also held on the one widthwise side of the rail, between the retaining means  204  and the rail, by a first (i.e., left in FIGS.  5 - 7 ) horizontal upper surface, provided with holes (not shown) that are connected to a source of vacuum (not shown). The fabric&#39;s marginal edge portion  131  is on the other widthwise side of the rail  101  and is free to move widthwise movement towards the rail&#39;s upward facing opening  119  or  127 .  
         [0062]    Step 5. FIG. 5B shows a fabric inserting wheel  205  of the assembly machine  201 . The wheel  205  can be a conventional fabric inserting wheel, such as is described in U.S. Pat. No. 5,127,143. The circumferential edge of the wheel  205  is rolled, preferably repeatedly, along the length of the rail and over the fabric F where the fabric is directly atop the rail&#39;s upward facing opening  119  or  127 . Preferably, this rolling passage of the wheel  205  over the fabric and the rail&#39;s upward facing opening is in both lengthwise directions. The circumferential edge of the wheel  205  is pressed slightly downwards during each rolling passage over the fabric, so that the wheel enters the rail&#39;s upward facing opening, and the circumferential edge of the wheel is preferably pressed further downward in the upward facing opening during each subsequent rolling passage, past the gap  125  or  130  between the adjacent uppermost fabric locking shoulders and preferably down to the cross web  111 . Indeed, once the wheel  205  reaches its maximum allowable depth in the rail&#39;s channel  106 , the assembly machine  201  preferably retracts the wheel. Since only the fabric&#39;s remainder  139  is held tight against widthwise movement during this step, the lengthwise passage(s) of the wheel  205  over the upward facing opening  119  or  127  pull the fabric&#39;s stiff straight marginal edge portion  131  widthwise towards, and eventually into, the rail&#39;s upward facing opening and thereby form a temporary fabric fold  159  in the rail&#39;s channel  106 , beneath the upward facing opening. Thereafter, repeated rolling passages of the wheel  205  in the upward facing opening push the fabric&#39;s marginal edge portion  131  below the uppermost locking shoulders where the marginal edge portion is held between one of the uppermost locking shoulders and the cross web  111  as shown in FIG. 5C. Preferably, the width, flexibility and resilience of the fabric&#39;s stiff marginal edge portion  131  cause it to assume a generally U-shaped configuration as the wheel  205  pushes it through the gap  125  or  130  between the uppermost locking shoulders and allows it to become straight again after being pushed through the gap.  
         [0063]    Thereafter, as shown in FIGS.  5 D- 5 F, the remainder  139  of the fabric F can be tightly wrapped about the rail&#39;s front and rear walls,  104 ,  105  as a decorative covering for the rail and also to ensure that the fabric&#39;s stiff marginal edge portion  131  is securely held by the locking shoulders. The four steps (6-9) of this method are as follows:  
         [0064]    Step 6. As seen in FIG. 5D, the retaining means  204  of the assembly machine  201  carries the fabric remainder  139  from the one (left) widthwise side of the rail  101  to its opposite (right) widthwise side. This is done only after turning off the source of vacuum (not shown) to the holes in the first (left) horizontal upper surface on the one widthwise side of the rail  101 . Then, the retaining means  204  holds the fabric remainder  139  on the other (right) widthwise side of the rail against unwanted movement towards the rail&#39;s upward facing opening  119  or  127  and the one (left) widthwise side of the rail. Preferably, the fabric remainder  139  is also then held on the other widthwise side of the rail by a second (i.e., right in FIGS.  5 - 7 ) horizontal upper surface, which is on the other (right) widthwise side of the rail, between the first retaining means  204  and the rail, and which has holes (not shown), connected to a source of vacuum (not shown).  
         [0065]    Step 7. As shown in FIG. 5E, the rail holder  203  slightly releases the ends of the rail  101  by sliding apart the holder blocks  203 A, 203 B. At the same time, the retaining means  204  releases somewhat its grip on the remainder  139  of the fabric F. The rail is then rotated 360 degrees in the direction away from the retaining means  204 , causing the fabric remainder  139  to be wrapped completely around the rail and overlie its originally upward facing opening  119  or  127  (which is again upward facing in FIG. 5E).  
         [0066]    Step 8. As also shown in FIG. 5E, the wheel  205  again rolls, preferably repeatedly, along the length of the rail  101  over the fabric F where it is directly atop the rail&#39;s upward facing opening  119  or  127 . As in step 5 (FIGS. 5B and 5C), a fabric fold  137  or  147  is formed in the rail&#39;s channel  106 , beneath the upward facing opening, because the retaining means  204 , on the opposite (right) widthwise side of the rail, allows controlled movement of the fabric remainder  139  towards the rail&#39;s upward facing opening  119  or  127  and the one (left) widthwise side of the rail.  
         [0067]    Step 9. As shown in FIG. 5F, the fabric fold  137  or  147  is secured inside the channel  106 , beneath the upward facing opening  119  or  127 , by a lengthwise spline  135  or  149  which is preferably wider than the adjacent gap  125  or  130  between the adjacent locking shoulders, above the fabric loop and the spline. The spline is preferably inserted longitudinally from an open end (not shown) of the rail, adjacent to one of the holder blocks  203 A, 203 B. The spline  135  or  149  lies within the fabric fold  137  or  147 . When the fabric remainder  139  is pulled taught, the spline locks against the fabric&#39;s stiff marginal edge portion  131  and the locking shoulders beneath the upward facing opening.  
         [0068]    The product of FIG. 2A (where a blind fabric F is attached to the top of a rail  101  and a valance fabric V is attached to the bottom of the rail) can be made by steps 1-6, above (FIGS.  5 A- 5 D), followed by steps 6A and 6B, as follows:  
         [0069]    Step 6A As shown in FIG. 6A, with the retaining means  204  of the assembly machine  201  holding the remainder  139  of a blind fabric F on the opposite (right) widthwise side of the rail  101 , the rail is rotated over 180 degrees in the direction away from the retaining means  204  and the fabric remainder  139 .  
         [0070]    Step 6B As shown in FIG. 6B, the retaining means  204  carries the fabric remainder  139  back to the one (left) widthwise side of the rail  101 , so that the remainder no longer covers the rail&#39;s upward facing opening  119  or  127 . This is done only after turning off the source of vacuum (not shown) to the second horizontal upper surface on the opposite (right) widthwise side of the rail  101 . Preferably, the retaining means  204  then holds the fabric remainder  139  on the one (left) widthwise side of the rail against unwanted movement towards the rail&#39;s upward facing opening  119  or  127  and the other (right) widthwise side of the rail. The holes in the first horizontal upper surface, on the one (left) widthwise side of the rail, are then connected to the source of vacuum (not shown).  
         [0071]    Thereafter, steps 2-6 (FIGS.  5 A- 5 D) are repeated using a valence fabric V after rotating the rail  101  by 180 degrees, so that its other opening  127  or  119  faces upward.  
         [0072]    The product of FIG. 3A (where a blind fabric F is attached to the top of a rail  101  and covers its front wall  103 ) can be made by steps 1-6, above (FIGS.  5 A- 5 D), followed by step 6A (FIG. 6A) and then steps 8-9, above (FIGS.  5 E- 5 F).  
         [0073]    The product of FIG. 3B (where a blind fabric F, without a stiff straight marginal edge portion, is attached to the top and bottom of a rail  101  and covers its front wall  103 ) can be made by steps 7A-7D (FIGS.  7 A- 7 D) as follows:  
         [0074]    Step 7A. As shown in FIG. 7A, the rail  101  is placed in the stationary rail holder  203  of the assembly machine  201 . The fabric F is then laid over the rail and its upward facing opening  119 , 127 , so that on each of its widthwise sides, there is enough of a fabric width, so that it will not all be pushed into the rail by the fabric inserting wheel  205  of this invention. The first retaining means  204 , on the one (left) widthwise side of the rail and preferably the first horizontal surface, the holes in the upper surface of which are connected to a source of vacuum, hold the width of fabric on its one widthwise side against unwanted movement towards the rail&#39;s upward facing opening  119  or  127  and toward its other (right) widthwise side.  
         [0075]    Step 7B. As shown in FIG. 7B, the fabric inserting wheel  205  passes, preferably repeatedly, along the length of the rail  101  and over the fabric F where the fabric is directly atop the rail&#39;s upward facing opening  119  or  127 , thereby forming a fabric fold  137 , 147  in the rail&#39;s channel  106 , beneath the upward facing opening.  
         [0076]    Step 7C. As shown in FIG. 7C, a lengthwise spline  135 , 149  is inserted in one end of the rail  101  and into the fabric fold  137 , 147 .  
         [0077]    Step 7D As shown in FIG. 7D, the rail is rotated over 180 degrees, and steps 7B and 7C, above, are then repeated.  
         [0078]    The product of FIG. 2B (where a blind fabric F is attached to the top of a rail  101  and covers its front wall  104  and a valence fabric V is attached to the bottom of the rail  101  and covers its rear wall  105 ) can be made by: first making the product of FIG. 3A from the blind fabric F by steps 1-6, above (FIGS.  5 A- 5 D), step 6A (FIG. 6A), above, and then steps 8-9, above (FIGS.  5 E- 5 F); then step 6B (FIG. 6B), above; and then repeating steps 1-6, above (FIGS.  5 A- 5 D), step 6A (FIG. 6A), above, and then steps 8-9, above (FIGS.  5 E- 5 F) with the valence fabric V, instead of the blind fabric F.  
         [0079]    This invention is, of course, not limited to the above-described embodiments which may be modified without departing from the scope of the invention or sacrificing all of its advantages. In this regard, the terms in the foregoing description and the following claims, such as “lengthwise”, “widthwise”, “upwardly”, “uppermost”, “downwardly”, “vertically”, “horizontally”, “upper”, “lower”, “left”, “right”, “top” and “bottom”, have been used only as relative terms to describe the relationships of the various elements of the rail of the invention for fabric coverings for architectural openings.  
         [0080]    For example, the fabric inserting wheel  205  of the assembly machine  201  need be rolled only once or a few times along the length of the rail over the fabric F and the rail&#39;s upward facing opening  19 , 119  or  127  while being pressed downwards in step 5 (FIG. 5B) and step 8 (FIG. 5E), above, but this would require a fabric inserting wheel of relatively large diameter which would tend to stress the fabric F, V being attached to the rail  1 , 101 . By comparison, the fabric inserting wheel  205  can have a significantly smaller diameter and will not tend to stress the fabric being attached to the rail, provided it is repeatedly rolled along the length of the rail over the fabric and the upward facing opening while being pressed downwards in steps 5 and 8.  
         [0081]    Likewise, pairs of fabric locking shoulders  21 , 23 , 121 , 123 ,  141 , 143  on opposite widthwise sides of each of the upper and lower portions  7 , 9 ,  107 , 109  of the channel  6 , 106  of the rail  1 , 101  are preferred, but only one such shoulder is needed in each of the upper and lower portions of the rail&#39;s channel.

Summary:
An elongate hollow rail for a fabric covering for an architectural opening, such as a bottom rail for a fabric roller blind or a top or bottom rail for a roman shade, having an upper portion with a lengthwise upper opening in the top of the rail and being characterized by a pair of lengthwise upper locking shoulders in the interior of the upper portion on walls on opposite widthwise sides of the upper opening and/or the upper locking shoulders being wedge-shaped and pointing inwardly of the upper portion and away from the upper opening, and/or the wall oh a first widthwise side of the bottom rail extending above the wall on the opposite second widthwise side of the bottom rail about the openings and a method for attaching a fabric to a locking shoulder within an elongate hollow rail for a fabric covering for an architectural opening having a lengthwise upper opening in an upper portion of the rail, by the steps of securing the rail to a stationary support structure with its lengthwise upper opening facing upwards, overlaying the rail and its upper opening and walls with a fabric having a stiff straight marginal edge, so that the stiff marginal edge lies parallel and adjacent to a wall on a widthwise side of the rail and the remainder of the fabric extends widthwise away from the stiff marginal edge and the rail and its other wall, pushing the fabric into the upper opening by rolling the circumferential edge of a fabric inserting wheel against the top of the fabric and lengthwise along, and inwardly of, the upper opening while allowing the stiff marginal edge to move widthwise towards the upper opening but preventing the remainder of the fabric from moving widthwise towards the upper opening; and then, pushing the stiff marginal edge into the upper opening so that the marginal edge engages the locking shoulder by again rolling the fabric inserting wheel against the top of the fabric and lengthwise along, and inwardly of, the upper opening while preventing the remainder of the fabric from moving widthwise towards the upper opening.