Lexical Analysis
----------------

Comments are enclosed in /* and */ and may span several lines.
Comments do not nest. Blanks, tabs, returns, newlines, and comments
are skipped during lexical analysis.

Identifiers (terminals as well as nonterminals) must begin with
a letter, and consist of letters and digits. The underscore counts
as a letter.

Program fragments are enclosed in %{ and %}. They do not nest.
Furthermore, they are immediately copied to the generated parser
during lexical analysis of the specification (so that there is no
danger of overflowing the generator's matching buffer).

For the tokens and attributes returned by the scanner of the parser
generator see the following table:

Lexeme				Token		Attribute

blank				-		-
tab				-		-
return				-		-
newline				-		-
/* comment */			-		-
EOF				E_O_F		-
%%				SDEL		-
%{ program text %}		PROG		-
%token				TOKEN		-
%start				START		-
%empty				EMPTY		-
letter, followed by
  letters or digits		IDENT		pointer to name
:				COLON		-
;				SEMIC		-
|				BAR		-


Syntax of the Specification Language (LR Parsing)
-------------------------------------------------

specification	:  definitions SDEL rules E_O_F
		|  definitions SDEL rules SDEL utilities E_O_F
		;

utilities	:  /* epsilon */
		|  utilities PROG
		;

definitions	:  /* epsilon */
		| definitions definition
		;

definition	:  TOKEN tokenlist
		|  START IDENT
		|  PROG
		;

tokenlist	:  IDENT
		|  tokenlist IDENT
		;

rules		:  /* epsilon */
		|  rules rule
		;

rule		:  IDENT COLON alternatives SEMIC
		;

alternatives	:  alternative
		|  alternatives BAR alternative
		;

alternative	:  EMPTY
		|  EMPTY PROG
		|  sequence
		|  sequence PROG
		;

sequence	:  IDENT
		|  sequence IDENT
		;