(flex.info.gz) Why can't flex understand this variable trailing context pattern?

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 Why can't flex understand this variable trailing context pattern?
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      To: Gregory Margo <gmargo@newton.vip.best.com>
      Subject: Re: flex-2.5.3 bug report
      In-reply-to: Your message of Sat, 23 Nov 1996 16:50:09 PST.
      Date: Sat, 23 Nov 1996 17:07:32 PST
      From: Vern Paxson <vern>
 
      > Enclosed is a lex file that "real" lex will process, but I cannot get
      > flex to process it.  Could you try it and maybe point me in the right direction?
 
      Your problem is that some of the definitions in the scanner use the '/'
      trailing context operator, and have it enclosed in ()'s.  Flex does not
      allow this operator to be enclosed in ()'s because doing so allows undefined
      regular expressions such as "(a/b)+".  So the solution is to remove the
      parentheses.  Note that you must also be building the scanner with the -l
      option for AT&T lex compatibility.  Without this option, flex automatically
      encloses the definitions in parentheses.
 
      		Vern
 

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(flex.info.gz) The | operator is not doing what I want

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(flex.info.gz) The ^ operator isn't working