\doc{Syntax descriptions}
\ref{grammar}
\ref{syntax}

The syntax of LP is described using equations of the form
\begin{verbatim}
\s{term} ::= \s{simpleId} | \s{simpleId} \qf{(} \s{term}+, \qf{)}
\end{verbatim}
that are interpreted according to the following conventions to mean that a
\s{term} is either a simple identifier or a simple identifier followed by
a parenthesized list of terms separated by commas.

\begin{description}
\dt \f{chars} or \qf{chars}
\dd A terminal \dlink{symbols}{symbol}
\dt \s{chars}
\dd A construct defined by a syntax equation
\dt \v{e} \v{f}               
\dd An \v{e} followed by (whitespace and) an \v{f}
\dt \v{e} | \v{f}
\dd An \v{e} or an \v{f}
\dt \v{e} ~ \v{f}
\dd An \v{e} that is not an \v{f}
\dt (\v{e})
\dd An \v{e} as a syntactic unit, as in (\v{e} | \v{f}) \v{e}.  Without
parentheses, \v{e} | \v{f} \v{e} is interpreted as \v{e} | (\v{f} \v{e}).
\dt [\v{e}]
\dd An optional \v{e}
\dt \v{e}* or \v{e}*, or \v{e}*[,]
\dd Zero or more \v{e}'s, separated respectively by nothing, commas, or
optional commas.
\dt \v{e}+ or \v{e}+, or \v{e}+[,]
\dd One or more \v{e}'s,  separated respectively by nothing, commas, or
optional commas.
\end{description}