% This macro source file is from the four volume series
% "TeX in Practice" by Stephan von Bechtolsheim, published
% 1993 by Springer-Verlag, New York.
% Copyright 1993 Stephan von Bechtolsheim.
% No warranty or liability is assumed.
% This macro may be copied freely if no fees other than
% media cost or shipping charges are charged and as long
% as this copyright and the following source code itself
% is not changed. Please see the series for further information.
%
% Version: 1.0
% Date: May 1, 1993
%
%
% This source code is documented in 25.1.21.1, p. III-345.
% Original source in file "macros5.TEX", starting line 1595.
\wlog{L: "ifx-def.tip" ["macros5.TEX," l. 1595, p. III-345]}%
% This file DOES belong to format "texip."
\catcode`\@ = 11
\newif\if@Def
\def\XDefinedConditional #1{% 
    TT\fi
    \ifx #1\@AlwaysUndefinedToken
        \@Deffalse
    \else
        \@Deftrue
    \fi
    \if@Def
}
\catcode`\@ = 12