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: 
BACKGROUND 
       [0001]    The present disclosure relates to the field of joist and truss construction. In particularly the disclosure relates to a broad spectrum of joist&#39;s or trusses having T-shaped chords with the benefits of adjustable length. 
         [0002]    Current joist designs offer different design types and can fall into two general categories, open web truss or closed web joist. Both have disadvantages for the consumer. 
         [0003]    One type of conventional open web truss which is used for supporting building floor and roof structures and the like is formed by two parallel wooden chords, such as 2×4 or 2×3 dimensions, or the use of composite lumber such as Laminated Veneer Lumber (LVL), arranged one over the other interconnected by webs of steel or wood. The webs may be attached by gluing or by sheet metal connector plates having tamped teeth protruding out allowing them to embed into the wooden chords. Such a truss is generally manufactured in a factory and transported to a construction site for installation as a component of the building. This type of truss is known in the art of trusses as an open web truss and has the ability to be designed with the chord being oriented either in the flat or wide direction or vertically or the narrow direction. While the truss with the flat lumber suffers from not enough material for strength the vertically assembled truss suffers from too narrow of a nailing surface. 
         [0004]    It is also known in the art of joist design to build a solid web joist consisting of two parallel wooden chords connected by a continuous solid web such as plywood or Oriented Strand Board (OSB). Such a joist suffers from having the solid web which doesn&#39;t leave any area for utilities such as plumbing, electrical or duct work to pass through them. 
         [0005]    There are current designs combining both features of the solid web joist and an open web truss. These combinations are limited in production due to difficulty in manufacturing or to weaknesses due to lumber orientation. 
         [0006]    Therefore there is a need for a joist that can combine the strength of a solid web joist with the capabilities of an open web truss and the flexibility of an adjustable length which prior art has not addressed. 
       SUMMARY 
       [0007]    The disclosed device is directed towards a strong open web truss formed from an upper chord and a lower chord that are interconnected by diagonal and/or vertical webs. The chords are T-shape providing strength in the vertical direction and giving a wider nailing surface in the horizontal direction. An extension portion is coupled to the upper chord and lower chord with a self-locking bulbous rabbet proximate the web at each end allowing the length of the truss to be adjusted. Typically the truss is assembled from wooden components. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]    The embodiments of the truss of the prescribed invention are shown in detail below with reference to attached drawings. 
           [0009]      FIG. 1  is a partial elevation view of an exemplary truss. 
           [0010]      FIG. 2  illustrates a complete isometric view of an exemplary truss. 
           [0011]      FIG. 3  is a perspective view of a T-shaped chord. 
           [0012]      FIG. 4  is a cross sectional end view of the T-shaped chord and connection to the end adjustable block using a self-locking bulbous rabbet. 
           [0013]      FIG. 5  is an exploded cross sectional view of the self-locking bulbous rabbet in detail. 
       
    
    
     DETAILED DESCRIPTION 
       [0014]    Persons of ordinary skill in the art will realize that the following disclosure is illustrative only and not in any way limiting. Other embodiments of the invention will readily suggest themselves to such skilled persons having the benefit of this disclosure. 
         [0015]    This disclosure describes a truss with T-shaped chords. The T-shaped chord includes a horizontal section connected to a vertical leg section approximate the center of the horizontal section forming a T. The chords will be interconnected by webs connected to the vertical section of the T-shaped chord. The truss includes extension sections at opposite ends of the chords. The extension sections extend beyond the webbing. The extension sections are configured to be adjustable allowing for proper fit upon installation of the truss. The extension sections generally having an I-beam cross sectional shape. Particularities for the adjustable sections are described below in more specific detail. 
         [0016]      FIG. 1  illustrates a partial elevation view of an exemplary truss. The truss  10  comprises an upper chord  21  combining a horizontal section  111  with a vertical section  11 A and a lower chord  21  combining a horizontal section  11  with a vertical section  11 A. In an exemplary embodiment, the upper and lower horizontal sections  11  can be made of solid lumber, such as 2×3 or 2×4 lumber or from composite lumber such as Laminated Veneer Lumber (LVL), GluLam, Laminated Strand Lumber (LSL) other types of composite lumber. The vertical section  11 A can be made of thinner lumber such as 1×3 or 1×4 or from the same thickness lumber as the horizontal section  11  is made. The vertical section may be made of solid lumber or composite lumber such as Laminated Veneer Lumber (LVL), GluLam, or Laminated Strand Lumber (LSL) or other types of composite lumber. The upper vertical section  11 A is coupled with a strut or web  13  to the lower vertical section  11 A. In an exemplary embodiment, the horizontal sections  11  and the vertical sections  11 A may be comprised from a single part or from individual parts. 
         [0017]    The web members  13  are generally arranged in a Warren or V type truss pattern. In another exemplary embodiment, the webs  13  may be arranged in a fan type arrangement where a vertical web  14  and a diagonal web  13  intersect at the vertical chord section  11 A. The web members  13 ,  14  may be connected to the vertical section of the chord  11 A by metal connector plates or by finger type adhesive joints or by some other fashion. The web members  13 ,  14  may be comprised of solid lumber, composite lumber or by metal, either stamped sheet metal or tubular. It will be appreciated by others in the art that other materials may be used while still embodying the spirit of the present invention. 
         [0018]    The adjustable truss  10  is constructed with an adjustable end block  12  at each end having a bulbous tenon  16  machined on the top and bottom edge allowing it to lock itself into the vertical sections  11 A. In the exemplary embodiment the truss  10  will have a similar bulbous rabbet  16  machined into the vertical sections at the extension to accept the adjustable end block  12 . The connection between the adjustable end block will be accomplished with glue. The adjustable end block  12  may be comprised of solid lumber or of composite lumber. The first web  13  may comprise a Bulbous rabbet  16  on one edge to receive a bulbous tenon  17  from one edge of the adjustable end block  12 . Those skilled in the art will appreciate that the bulbous tenon  17  and rabbet  16  is a self-locking connection and that it requires no clamping time for gluing, speeding up production time. 
         [0019]      FIG. 2  illustrates a complete isometric view of the invention in an exemplary form. In this exemplary embodiment, truss  10  includes an upper chord  21  comprised of a horizontal section  11  with a vertical section  11 A and a lower chord  21  comprised of a horizontal section  11  with a vertical section  11 A. The upper chord  21  is interconnected to the lower chord  21  by way of webs  13 ,  14  configured in a v-shape configuration with multiple spans. An opening  15  approximate the center of the span can be used to facility additional space needed for placement of plumbing or duct work. The opening  15  can be facilitated by a web  14  placed vertically at each end of the opening  15 . In another alternative exemplary truss, the web  14  maybe placed at the beginning of the webs  13  and the adjustable end block  12 . In this alternative embodiment the vertical web  14  may also include a bulbous rabbet  16  to receive the bulbous tenon  17 . It will be appreciated by others skilled in the art that other web configurations may be used. 
         [0020]      FIG. 3  is an illustration of a perspective view of the T-shaped chord. The T-shape chord  21  will be comprised of a flat horizontal section  11  and a vertical section  11 A. In an alternative exemplary form, the T-shaped chord  21  may be comprised of a horizontal section  11  and multiple vertical sections  11 A. Those skilled in the art will recognize that the T-shape offers strength in two directions, horizontally and vertically without the waste of using a larger solid piece of lumber and therefore making more efficient use of our timber resources. 
         [0021]      FIG. 4  is a cross sectional end view of the connection between the chords  21  and the adjustable end block  12 . In the exemplary truss  10  the chords  21  are connected to the adjustable end block  12  with a bulbous rabbet  16  and tenon  17  and facilitated with an adhesive. The vertical section  11 A of the chord  21  will have a bulbous rabbet  16  at the end of the truss  10  to accept the bulbous tenon  17  of the adjustable end block  12 . An adhesive may be applied between the bulbous rabbet  16  and the bulbous tenon  17 . 
         [0022]      FIG. 5  illustrates an exploded cross sectional View of the connection between the adjustable end block  12  and the chord  21 . The chord  21  comprised of the horizontal section  11  and the vertical section  11 A. The vertical section  11 A having a bulbous rabbet  16  to accept the bulbous tenon  17 . The bulbous tenon  17  comprised of a bulbous end  20  tapers to a narrower neck  18  and a chamfered section  19 . Likewise, the bulbous rabbet  16  comprised identically to accept the bulbous tenon  17 .

Summary:
The disclosed device is directed towards a truss comprising an upper T-shaped chord. A lower T-shaped chord is coupled to said upper chord. A plurality of web members are coupled to said T-shaped chords. An extension section is coupled to said upper T-shaped chord and said lower T-shaped chord approximate the web. Said extension section is configured to by adjustable by trimming.