Appendix A Syntax Table Notation

A syntax table consists of rules that have name and body:

The name and body of the rule are separated by the → symbol.

In the body of a rule there can be terminal symbols, language keywords, references to other rules, character classes in brackets, and expressions containing those primitives and expressions combined with operators '|', catenation, '*', '+', and '?'.

• Terminal symbols are in monospace font. A terminal symbol matches a literal input character.
• Language keywords are in bold font. A keyword matches a literal string of input characters.
• The names of the rules are in italic font.
• Symbols in brackets denote a character class. A character class matches a single input character belonging to the class. A character class can contain single terminal symbols represented in monospace font and ranges of characters. For example a character class [0 - 9 ] represents a character class that matches a single decimal digit. If the class starts with a caret character, '^', the class is inverted. For example a character class [^0 - 9 ] matches a single input character that is not a decimal digit.
• Expression e₀ | e₁ matches either e₀ or e₁.
• Expression e₀ e₁ matches a sequence of e₀ and e₁.
• Expression e* represents Kleene closure: e matches zero or more times.
• Expression e+ represents positive closure: e matches one or more times.
• Expression e? represents optionality: e matches zero or one time.
• Operator '|' has least precedence, then comes catenation. Operations '*', '+' and '?' have greatest precedence. Precedence can be overridden or clarified using parentheses.