Definitions for the Grammar Summary
Terminals are endpoints in a syntax definition. No other resolution is possible. Terminals include the set of reserved words and user-defined identifiers.
Nonterminals are placeholders in the syntax. Most are defined elsewhere in this syntax summary. Definitions can be recursive. The following nonterminals are defined in the of the C++ Language Reference:
constant, constant-expression, identifier, keyword, operator, punctuator
An optional component is indicated by the subscripted opt. For example, the following indicates an optional expression enclosed in curly braces:
{expressionopt}