In the syntax notation used in this document, syntactic
categories are indicated by italic, sans-serif
type, and literal words
and characters in constant width
listed on separate lines except in a few cases where a long set of
alternatives is marked by the phrase “one of”.
If the text of an alternative is too long to fit on a line, the text is continued on subsequent lines indented from the first one.
An optional terminal or non-terminal symbol is indicated by the subscript
indicates an optional expression enclosed in braces.