
<A NAME=tilde>

<TITLE>tilde</TITLE></A>
<b><a href=r37_idx.html>INDEX</a></b><p><p>



<B>~</B> _ _ _ <B>TILDE</B> _ _ _  _ _ _  _ _ _  _ _ _ <B>operator</B><P>
<P>
 
The <em>~</em> is used as a unary prefix operator in the left-hand 
sides of 
<A HREF=r37_0060.html>rule</A>s to mark 
<A HREF=r37_0061.html>free variable</A>s. A double tilde 
marks an optional 
<A HREF=r37_0061.html>free variable</A>. 
<P>
<P>
