From: JoelCSalomon@Gmail.com   
      
   whiskey wrote:   
   > how would a regular expression that matches a regular   
   > expression look like ?   
      
   Which flavor of regexp?  But that hardly matters; since parenthesis and   
   brackets must be matched in a valid regexp, regular expressions cannot   
   themselves be described by a regular language.   
      
   On Plan 9 systems, almost all regexp-using programs use the regexp   
   library.  Its syntax is given in   
   http://plan9.bell-labs.com/magic/man2html/6/regexp, in BNF.  (A Unix   
   port is available at http://swtch.com/plan9port/unix/).  POSIX regular   
   expressions are probably defined somewhere, I just don't know where.   
      
   --Joel   
   [POSIX REs are defined where you'd expect, in the POSIX standard. -John]   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)