Re: EBNF open letter (Fergus Henderson)
Sat, 17 Sep 1994 04:53:13 GMT

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Newsgroups: comp.compilers
From: (Fergus Henderson)
Keywords: parse, EBNF
Organization: Computer Science, University of Melbourne, Australia
References: 94-09-030
Date: Sat, 17 Sep 1994 04:53:13 GMT (John Rogers) writes:

>Are you aware of any ongoing work on standardizing EBNF? Perhaps an ANSI,
>IEEE, IEC, or ISO committee? If nothing is ongoing, then I might be
>interested in creating an informal committee for this. Would you be
>interested in being involved in the committee? Or would you just like me
>to keep you posted?

There's an extended BNF notation standardized as

BS6154, Method of defining -- Syntactic metalanguage, 1981

which is used by the Prolog DIS (Draft International Standard).
It includes the following symbols:

Symbol Meaning
------ -------
Unquoted characters Non-terminal symbol
" ... " Terminal symbol
' ... ' Terminal symbol
( ... ) Brackets
[ ... ] Optional symbols
{ ... } Symbols repeat zero or more times
= Defining symbol
; Rule terminator
| Alternative
, Concatenation
(* ... *) Comment

For example:

(* floating-point literals *)
float number token = integer constant, fraction, [exponent]

Note that the names of non-terminal symbols may be multiple words.

Fergus Henderson -

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