Notation

Throughout this section we will be using an extended version of the Backus-Naur Form (BNF) to describe the syntax of DependoBuf. The following table describes the symbols used in the notation:

Notation	Examples	Description
\(pat\)	\(lc\_letter\)	A non-terminal production.
\(::=\)	\(a ::= \texttt{a}\)	Definition. Represents the definition of a non-terminal.
\(\texttt{literal}\)	\(\texttt{message}\)	Terminal syntax. Represents exactly the characters you see.
\(\mid\)	\(\texttt{a} \mid \texttt{b}\)	Alternation. Represents a choice between two or more alternatives.
\([pat]\)	\([lc\_letter]\)	Optional. Represents zero or one occurrences of the enclosed pattern.
\(\lbrace pat\rbrace\)	\(\lbrace lc\_letter\rbrace\)	Repetition. Represents zero or more occurrences of the enclosed pattern.
\(\lgroup pat\rgroup\)	\(\lgroup lc\_letter\rgroup\)	Grouping. Represents a group of patterns.
\(pat_{\langle excl \rangle}\)	\(lc\_letter_{\langle \texttt{a} \mid \texttt{b}\rangle}\)	Exclusion. Represents the pattern except for the excluded characters.

It is important to note the distinction between \(\mid\) and \(\texttt{|}\) and between \(\lbrace \rbrace\) and \(\texttt{\{} \texttt{\}}\), however it should be clear from the context which one is being used.