What is the NLTK FCFG grammar standard/specification?
<p><strong>NLTK</strong> (Natural Language Toolkit) lets you parse a FCFG grammar using <code>nltk.FCFG.fromstring([grammar string here]).</code> Where is the FCFG grammar format specification*? I googled it to death, but all I could find was <a href="http://www.nltk.org/howto/grammar.html" rel="nofollow">this</a>. </p>

<p>*i.e. grammar language specification</p>