Writing obligatory

from The Collaborative International Dictionary of English v.0.48
Writing \Writ"ing\, n.
   1. The act or art of forming letters and characters on paper,
      wood, stone, or other material, for the purpose of
      recording the ideas which characters and words express, or
      of communicating them to others by visible signs.
      [1913 Webster]

   2. Anything written or printed; anything expressed in
      characters or letters; as:
      (a) Any legal instrument, as a deed, a receipt, a bond, an
          agreement, or the like.
      (b) Any written composition; a pamphlet; a work; a
          literary production; a book; as, the writings of
          Addison.
      (c) An inscription.
          [1913 Webster]

                And Pilate wrote a title . . . And the writing
                was, Jesus of Nazareth, the King of the Jews.
                                                  --John xix.
                                                  19.
          [1913 Webster]

   3. Handwriting; chirography.
      [1913 Webster]

   {Writing book}, a book for practice in penmanship.

   {Writing desk}, a desk with a sloping top for writing upon;
      also, a case containing writing materials, and used in a
      similar manner.

   {Writing lark} (Zool.), the European yellow-hammer; -- so
      called from the curious irregular lines on its eggs.
      [Prov. Eng.]

   {Writing machine}. Same as {Typewriter}.

   {Writing master}, one who teaches the art of penmanship.

   {Writing obligatory} (Law), a bond.

   {Writing paper}, paper intended for writing upon with ink,
      usually finished with a smooth surface, and sized.

   {Writing school}, a school for instruction in penmanship.

   {Writing table}, a table fitted or used for writing upon.
      [1913 Webster]
    
from Bouvier's Law Dictionary, Revised 6th Ed (1856)
WRITING OBLIGATORY. A bond; an agreement reduced to writing, by which the 
party becomes bound to perform something, or suffer it to be done. 
    

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