Please use the form below to search our dictionaries by entering a word you wish to define. (If you search this site to define words regularly, support this FREE site - Donate! )

Define the word BNF

BNF
     Backus-Naur Form (TTCN, ...)
     
     

BNF /B-N-F/ n. 1. [techspeak] Acronym for `Backus Normal Form' (later
   retronymed to `Backus-Naur Form' because BNF was not in fact a normal
   form), a metasyntactic notation used to specify the syntax of
   programming languages, command sets, and the like. Widely used for
   language descriptions but seldom documented anywhere, so that it must
   usually be learned by osmosis from other hackers. Consider this BNF for
   a U.S. postal address:

    ::=   
  
    ::=  |  "."
  
    ::=   [] 
                 |  
  
    ::= []   
  
    ::=  ","   
  
   This translates into English as: "A postal-address consists of a
   name-part, followed by a street-address part, followed by a zip-code
   part. A personal-part consists of either a first name or an initial
   followed by a dot. A name-part consists of either: a personal-part
   followed by a last name followed by an optional `jr-part' (Jr., Sr., or
   dynastic number) and end-of-line, or a personal part followed by a name
   part (this rule illustrates the use of recursion in BNFs, covering the
   case of people who use multiple first and middle names and/or initials).
   A street address consists of an optional apartment specifier, followed
   by a street number, followed by a street name. A zip-part consists of a
   town-name, followed by a comma, followed by a state code, followed by a
   ZIP-code followed by an end-of-line." Note that many things (such as the
   format of a personal-part, apartment specifier, or ZIP-code) are left
   unspecified. These are presumed to be obvious from context or detailed
   somewhere nearby. See also parse. 2. Any of a number of variants and
   extensions of BNF proper, possibly containing some or all of the
   regexp wildcards such as `*' or `+'. In fact the example above isn't
   the pure form invented for the Algol-60 report; it uses `[]', which was
   introduced a few years later in IBM's PL/I definition but is now
   universally recognized. 3. In {science-fiction fandom}, a `Big-Name
   Fan' (someone famous or notorious). Years ago a fan started handing out
   black-on-green BNF buttons at SF conventions; this confused the hacker
   contingent terribly.

BNF
     
        Backus-Naur Form.  Originally Backus Normal Form.
     
        [Jargon File]