Appendix B. Notation

Name ::= ...

Defines a grammar rule with name Name.

Rule1 | Rule2

Alternative: either Rule1 or Rule2.

Rule*

Zero or more occurrences of Rule.

Rule+

One or more occurrences of Rule.

Rule?

Zero or one occurrences of Rule.

'xyz'

An occurrence of xyz with proper tokenization. For example, 'case' doesn't match cases.