Extended Backus-Naur Form

language Any variation on the basic Backus-Naur Form (BNF)

meta-syntax notation with (some of) the following additional

constructs: square brackets "[..]" surrounding optional

items, suffix "*" for Kleene closure (a sequence of zero or

more of an item), suffix "+" for one or more of an item,

curly brackets enclosing a list of alternatives, and

super/subscripts indicating between n and m occurrences.

All these constructs can be expressed in plain BNF using extra

productions and have been added for readability and

succinctness.

(1995-04-28)