# [texhax] help with identifying some macros

Barbara Beeton bnb at ams.org
Fri Oct 16 15:04:37 CEST 2009

```phil taylor opines,

Barbara Beeton wrote: (and Barbara is never wrong)

hah!  you're saying that with tongue in
cheek, i hope!  and in fact, there was
a glitch in what i wrote -- the regular
\strut has height and depth that add up
to the dominant baseline separation;
the height and depth of a parenthesis
apply to \mathstrut .  however, the
purpose of both is to enforce a minimum
separation between lines.

> hope that makes sense.  this is plain tex,
> *very* plain tex.

but is it ?  On trying to compile it, I am told

! Undefined control sequence.
l.2     \[

which rather met my expectations.  So what /is/ it,
I am forced to ask ?!

what i meant, and wasn't as clear as
i should have been, is that the \halign
construction is plain tex, not the whole
example file.

it's usually possible to use plain tex
constructions within a latex environment
(and sometimes absolutely necessary, such
as when one is creating some .cls or .sty
files), but for an end user, usually not
a good idea.

P.S. I /was/ going to say that it would be far more
comprehensible if greater attention had been paid
to layout, but if -- as I suspect -- Paul Stanley
is using a speech synthesiser to examine the material,
then I am not sure that better layout would help.

yes, that's true.  thanks for the reminder,
phil.  this means that the computer file
of the texbook (already cited by someone
else) is one of the right places for paul
to look, although some of it may be tough
sledding, since it's an example of using