doc/refintro.tex: Fix indexed-nonterminal argument abbreviation.

The thing with the unfinished ellipsis causes a very unpleasant effect
where dots at different heights are separated only by a comma.
Reluctantly, I fix this by replacing the nearly approachable `\$alpha |
\beta | ...' notation with numeric superscripts.

diff --git a/doc/refintro.tex b/doc/refintro.tex
index 6d93b65..b0626c3 100644 (file)
--- a/doc/refintro.tex
+++ b/doc/refintro.tex
@@ -107,12 +107,14 @@ As a notational convenience, where an indexed nonterminal appears on the
 right-hand side of a production rule, each actual argument may be a sequence
 of alternative right-hand sides, separated by `$|$', rather than a a simple
 terminal or nonterminal symbol.  A complex indexing of this form, say
-$x[\alpha_1 | \beta_1 | \cdots, \ldots, \alpha_n | \beta_n | \cdots]$ means
-exactly the same as $x[a_1, \ldots, a_n]$ with the additional rules
+\syntax{$x$@[$\alpha_1^1$ @! $\alpha_1^2$ $| \cdots |$ $\alpha_1^{m_1},
+\ldots,$ $\alpha_n^1$ @! $\alpha_n^2$ $| \cdots |$ $\alpha_n^{m_n}$@]}
+means exactly the same as \syntax{$x$@[$a_1, \ldots, a_n$@]} with the
+additional rules
 \begin{quote}
-  \syntax{$a_1$ ::= $\alpha_1$ @! $\beta_1$ @! $\cdots$} \\
-  \hbox{}\qquad $\vdots$ \\
-  \syntax{$a_n$ ::= $\alpha_n$ @! $\beta_n$ @! $\cdots$}
+  \syntax{$a_1$ ::= $\alpha_1^1$ @! $\alpha_1^2$ $| \cdots |$ $\alpha_1^{m_1}$} \\*
+  \hbox{}\qquad $\vdots$ \\*
+  \syntax{$a_n$ ::= $\alpha_n^1$ @! $\alpha_n^2$ $| \cdots |$ $\alpha_1^{m_n}$}
 \end{quote}
 where $a_1$, \ldots, $a_n$ are new nonterminal symbols.