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 OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to the general art of ladders, and to the particular field of accessories for ladders. 
   2. Discussion of the Related Art 
   Many tasks require the use of an extension ladder to complete. Just about any work on or near the ceiling of a room will require a ladder. 
   Using a ladder while performing a task may require skill, balance and dexterity. These traits can, and are, generally acquired by workers and craftsmen. However, no matter how proficient a worker is, he must still have some part of his concentration directed to maintaining his balance on the ladder while competing a task. 
   For example, a paper hanger must balance on a ladder while feeding paper from a roll, applying adhesive, and keeping the paper in place. While many paper hangers successfully achieve these goals, it would make their jobs easier if one or more of these tasks could be carried out by an accessory. 
   Therefore, there is a need for an accessory for a ladder that will permit a worker to direct most of his concentration to completing the task. 
   More specifically, there is a need for an accessory for a ladder that will assist a paper hanger in directing as much of his concentration on the task of hanging paper as possible. 
   Any accessory that is intended to make a task easier should not require a great deal of work to set up, or its objective will be vitiated. Therefore, there is a need for an accessory for a ladder that will assist a paper hanger in directing as much of his concentration on the task of hanging paper as possible and which is easy to assemble and to disassemble from a ladder. 
   To be most effective, any accessory that is intended to hold work items on a ladder must hold those items in the most convenient location on the ladder where those items will be easily accessible to a worker balancing on the ladder. Otherwise, the objectives of the accessory may be defeated. 
   Therefore, there is a need for an accessory for a ladder that will assist a paper hanger in directing as much of his concentration on the task of hanging paper as possible and will locate the items needed for the task in a position that is most convenient for the worker. 
   Principal Objects of the Invention 
   It is a main object of the present invention to provide an accessory for a ladder that will permit a worker to direct most of his concentration to completing the task. 
   It is another object of the present invention to provide an accessory for a ladder that will assist a paper hanger in directing as much of his concentration on the task of hanging paper as possible. 
   It is another object of the present invention to provide an accessory for a ladder that will assist a paper hanger in directing as much of his concentration on the task of hanging paper as possible and which is easy to assemble and to disassemble from a ladder. 
   It is another object of the present invention to provide an accessory for a ladder that will assist a paper hanger in directing as much of his concentration on the task of hanging paper as possible and will locate the items needed for the task in a position that is most convenient for the worker. 
   SUMMARY OF THE INVENTION 
   These, and other, objects are achieved by an accessory that includes a trigger-operated clamp, a paper supporting roller, a masking tape holder, a paper cutter, and a tape cutter. 
   The accessory is easily clamped onto a rail of an extension ladder and will support paper and tape in position to be easily reached and easily manipulated by a worker balancing on the ladder. After a job has been completed, the accessory embodying the present invention is easily removed from the ladder. 

   
     BRIEF DESCRIPTION OF THE DRAWING FIGURES 
       FIG. 1  is a perspective view of an accessory for use on a ladder during a paper hanging operation. 
       FIG. 2  is a side elevational view of an accessory for use on a ladder during a paper hanging operation. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Other objects, features and advantages of the invention will become apparent from a consideration of the following detailed description and the accompanying drawings. 
   Referring to the Figures, it can be understood that the present invention is embodied in an accessory  10  for use on a ladder to support paper and tape rolls on the rail of the ladder in a position that is convenient to a user. 
   Accessory  10  comprises a central support bar  12  which has a first end  14 , a second end  16 , a first side wall  18 , a second side wall  20 , and a longitudinal axis  22  which extends between first end  14  and second end  16 . 
   A tape roll-supporting unit  26  is mounted on second end  16  of central support bar  12 . Tape roll-supporting unit  26  includes an axle  30  mounted on support bar  12  and which extends between first and second side walls  18  and  20  of support bar  12  and transversely to longitudinal axis  22  of the support bar  12 . A first tape roll holder  32  is rotatably mounted on the axle  29  adjacent to first side wall  18 , and a second tape roll holder  34  is rotatably mounted on axle  30  adjacent to second side wall  20  of the support bar  12 . 
   Tape mounted on the tape roll-supporting unit  26  will be fed off the rolls in a manner known to those skilled in the art. 
   A tape cutter element  40  is mounted on support bar  12  and includes a first end  42  located adjacent to first side wall  18  of the support bar  12 , a second end  44  located adjacent to second side wall  20  of the support bar  12 , and a longitudinal axis  46  which extends between first end  42  and second end  44  of tape cutter element  40  and which is oriented to extend transversely of longitudinal axis  22  of support element  12 . A cutting edge  48  is on tape cutter element  40  and is used to cut lengths of tape in a manner known to those skilled in the art. 
   A paper roll holder element  50  is mounted on supporting bar  12  adjacent to first end  14  of the supporting bar  12 . Element  50  includes a mounting bolt  52  fixed to supporting bar  12 , a base element  54  in abutting contact with second side wall  20  of supporting bar  12  and is fixed to mounting bolt  52 . 
   A roller element  56  is rotatably mounted on mounting bolt  52  and paper rolls are supported on the roller element  56  in a manner known to those skilled in the art. 
   A paper control arm  60  has a first end  62  pivotally fixed to tape cutter element  40  and a second end  64  located adjacent to roller element  56 . As can be understood from the Figures, paper roll holder element  50  extends parallel to tape cutter element  40 . 
   A paper cutting blade  70  is mounted on first end  14  of supporting bar  12  and includes a first end  72  fixed to supporting bar  12 , a second end  74 , and a longitudinal axis  76  which extends between first end  72  and second end  74  of paper cutting blade  70  and which is oriented to be parallel to paper roll holder element  50  and to extend transversely to longitudinal axis  22  of supporting element  12 . 
   A paper cutting edge  78  is located on paper cutting blade  70  to cut paper drawn thereover in a manner known to those skilled in the art. 
   A ladder attachment unit  80  includes a main bar  82  slidably mounted on tape cutter element  40  adjacent to second end  44  of the tape cutter element  40 . Main bar  82  includes a first end  84 , a second end  86 , and a longitudinal axis  88  which extends between first end  84  and second end  86  of the main bar  82  and is oriented transversely of longitudinal axis  46  of tape cutter element  40  and transversely of longitudinal axis  22  of supporting element  12 . 
   Main bar  82  further includes a first edge  90  which is a top edge when ladder attachment unit  80  is in use, a second edge  92  which is a bottom edge when ladder attachment unit  80  is in use, a stop element  94  on second end  84  of the main bar  82 , and a first ladder-engaging clamp element  96  located on first end  84  of the main bar  82 . 
   A handle unit  100  is mounted on main bar  82  and includes a hand-held element  102  having a bore  104  defined therethrough and through which main bar  82  is slidably accommodated. Unit  100  further includes a trigger element  106  pivotally mounted on hand-held element  102 , and a second ladder engaging-clamp element  108  on the hand-held element  102 . Second ladder-engaging clamp element  108  is oriented to face first ladder-engaging element  96  with a rail of a ladder interposed therebetween when ladder attachment unit  10  is in use. 
   A mechanism  120 , such as a ratchet and pawl mechanism, or other such mechanism that is known to those skilled in the art, connects trigger element  106  to main bar  82  of ladder attachment unit  80  in a manner such that operation of the trigger element  106  causes the main bar  82  to move first ladder-engaging clamp element  96  toward second ladder-engaging clamp element  108  to clamp the rail of the ladder therebetween and mount unit  10  on the rail of the ladder. 
   Operation of unit  10  can be understood by one skilled in the art based on the teaching of the foregoing disclosure, and thus will not be discussed in detail. Unit  10  is located on the rail of a ladder in a chosen position, trigger element  106  is operated to draw clamp element  96  toward clamp element  108  and clamp the rail of the ladder therebetween. Paper is mounted on unit  50  and tape on unit  26 . Paper is drawn over cutting edge  76  and cut when a desired length of paper is drawn. Tape is drawn off tape rolls and cut using cutting edge  46  for use with the paper. When a job is completed, unit  10  can be disassembled from the ladder and moved to a position convenient for the next job. 
   It is understood that while certain forms of the present invention have been illustrated and described herein, it is not to be limited to the specific forms or arrangements of parts described and shown.

Summary:
An accessory includes a handle-operated clamp and is mounted on a rail of a ladder, such as an extension ladder, to hold paper and tape in position to be easily accessed by a worker balancing on the ladder.