tex using the wrong macro

Question

Out of curiosity I tried to weave the bibtex.web source code and compile the resulting bibtex.tex with tex. I got some errors which led me to investigate; I'm sure my confusion stems from incorrect assumptions on my part.

The errors were of the missing $ kind, but point to the use of a wrong macro. Weaved tex-files use the webmac.sty style file. In it are macros such as \A, \As, \E , \ET and \ETs. The \E macro should be used in a math environment.

An example of an error is:

! Missing $ inserted.
<inserted text> 
                $
<to be read again> 
                   \cdot 
\E->\cdot 
          10^
<argument> 39, 58, 60\E
                       Ts61
\note ...ndent 2em\baselineskip 10pt\eightrm #1~#2
                                                  .\par }
l.1135 \As39, 58, 60\ETs61.

What this shows is that the \ETs macro is only being read as far as the \E part. Why does this happen, and why doesn't it happen with similarly named and used \As macros?

Edit: I should add that the behaviour remains the same when adding spaces after the offending macro.

Answer 1

After the initial lines about recent changes, the bibtex.ch file has

% [0] Let bibtex.tex work with latest webmac (which defines \ET, hence
% making E active loses).
@x
\catcode`E=13 \uppercase{\def E{e}}
\def\\#1{\hbox{\let E=\drop\it#1\/\kern.05em}} % italic type for identifiers
@y
\let\maybe = \iffalse % process only changed sections
@z

So you need to have both bibtex.web and bibtex.ch (I downloaded them from http://tug.org/svn/texlive/trunk/Build/source/texk/web2c/) and call

weave bibtex.web bibtex.ch

Then, running pdftex or tex on the generated bibtex.tex file will produce a correct output without errors.