doc/refintro.tex: Split the syntax notation into subsections.

I'd be happier if these were subsubsections, honestly.

diff --git a/doc/refintro.tex b/doc/refintro.tex
index b0626c3..6689505 100644 (file)
--- a/doc/refintro.tex
+++ b/doc/refintro.tex
@@ -90,11 +90,17 @@ manual describes the base system as provided in the distribution.
 Fortunately, Sod is syntactically quite simple.  The notation is slightly
 unusual in order to make the presentation shorter and easier to read.
 
+
+\subsection{Empty production}
+
 The letter $\epsilon$ denotes the empty nonterminal
 \begin{quote}
   \syntax{$\epsilon$ ::=}
 \end{quote}
 
+
+\subsection{Indexed nonterminals}
+
 Anywhere a simple nonterminal name $x$ may appear in the grammar, an
 \emph{indexed} nonterminal $x[a_1, \ldots, a_n]$ may also appear.  On the
 left-hand side of a production rule, the indices $a_1$, \ldots, $a_n$ are
@@ -118,6 +124,9 @@ additional rules
 \end{quote}
 where $a_1$, \ldots, $a_n$ are new nonterminal symbols.
 
+
+\subsection{Common indexed productions}
+
 The following indexed productions are used throughout the grammar, some often
 enough that they deserve special notation.
 \begin{itemize}