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From: ogawa@orion.arc.nasa.gov (Arthur Ogawa)
Newsgroups: comp.text.tex
Subject: Re: How to include unbalanced brackets `}' in macro substitution?
Summary: use \bgroup and \egroup
Message-ID: <1991Feb5.073200.6315@news.arc.nasa.gov>
Date: 5 Feb 91 07:32:00 GMT
References: <1991Feb5.023920.20619@cs.ucla.edu>
Sender: usenet@news.arc.nasa.gov (USENET Administration)
Organization: /usr/local/lib/rn/organization
Lines: 15

You want to define as follows:

\long\def\beginvcenter{\vbox to\vsize\bgroup\vfil}%
\def\endvcenter{\vfil\egroup}%

THen you can write:

\beginvcenter
   *TEXT*
\endvcenter

Be careful: the resulting box will always require a page of its own!

Cheers,
Art Ogawa