# Presence of non-plain TeX control sequences in the TeXbook?

I was browsing the TeXbook source file texbook.tex from CTAN. In it, I came across the control word pair \begintt, \endtt (e.g., lines 445–447, looks like for marking up source code). But I couldn't find them mentioned in the TeXbook, nor are they in Knuth's plain.tex macro file. I also tried \$ tex '\show\begintt' on the command line, which returns undefined.

I'm wondering, is texbook.tex from CTAN the actual original file that Knuth authored? Because it just seems odd (to me, anyway) that he would have used any macros when writing his original book that he wouldn't have included as "plain TeX".

• plain tex are what are described in the texbook as "basic macros" it isn't intended to use plain tex for writing documents, but instead a more extensive format, the texbook uses manmac, other fromats are amstex, latex, etc – David Carlisle Aug 29 at 22:30
• @DavidCarlisle That gives a good perspective—thank you. – yroc Aug 29 at 22:33

\begintt and \endtt are defined in manmac.tex

\outer\def\begintt{$$\let\par=\endgraf \ttverbatim \parskip=\z@ \catcode\|=0 \rightskip-5pc \ttfinish} {\catcode\|=0 |catcode|\=\other % | is temporary escape character |obeylines % end of line is active |gdef|ttfinish#1^^M#2\endtt{#1|vbox{#2}|endgroup$$}}


Actually \endtt is not a macro, but just a delimiter for deciding where to stop the verbatim listings.

The source of the TeXbook starts with

% This manual is copyright (C) 1984 by the American Mathematical Society.
% All rights are reserved!
% The file is distributed only for people to see its examples of TeX input,
% not for use in the preparation of books like The TeXbook.
% Permission for any other use of this file must be obtained in writing

• I see, thank you. Would manmac.tex macros be considered part of "plain TeX"? – yroc Aug 29 at 22:20
• @yroc -- manmac` is also the macro set used for the METAFONTbook. – barbara beeton Aug 30 at 0:25