6. Language

6.1 Notation
1 In the syntax notation used in this clause, syntactic categories (nonterminals) are
indicated by italic type, and literal words and character set members (terminals) by bold
type. A colon (:) following a nonterminal introduces its definition. Alternative
definitions are listed on separate lines, except when prefaced by the words ‘‘one of’’. An
optional symbol is indicated by the subscript ‘‘opt’’, so that
{ expressionopt }
indicates an optional expression enclosed in braces.
2 When syntactic categories are referred to in the main text, they are not italicized and
words are separated by spaces instead of hyphens.
3 A summary of the language syntax is given in annex A.