is
to allow nonterminals to match <i>anything</i>;
so not just a valid tag, but also total gibberish, blanks or just nothing.
This &lsquo;invalid&rsquo; input will be captured as an empty string
(&ldquo;&rdquo;).
</p>
<p>
Having such a &lsquo;loose&rsquo; nonterminal in the middle of a pattern
does complicate the pattern matching process; it would require
<a href="http://en.wikipedia.org/wiki/Backtracking">backtracking</a>
to properly align the word &lsquo;in&rsquo;
when matching input &ldquo;put foo in in 