Statements:

comment	:	// anything-except-newline
	|	/* anything-except-*/ */

identifier	:	[a-zA-Z][a-zA-Z0-9-]

integer	:	[0-9]+

string	:	'anything-except-single-quote'
	|	"anything-except-double-quote"

command	:	keyword attribute-list
	|	label : keyword attribute-list

keyword	:	identifier

label	:	identifier

attribute-list	:	empty
	|	attribute-list , attribute

attribute	:	attribute-name // only for logical attribute
	|	attribute-name = attribute-value // expression evaluated
	|	attribute-name := attribute-value // expression retained

attribute-name	:	identifier

attribute-value	:	string-expression
	|	logical-expression
	|	real-expression
	|	array-expression
	|	constraint
	|	variable-reference
	|	place
	|	range
	|	token-list
	|	token-list-array
	|	regular-expression