# [texhax] \mark causing a blank line

bnb at ams.org bnb at ams.org
Sun Jun 21 14:55:48 CEST 2015

```    The plain TeX code below might not be a minimal example, but it's
self-documenting!

Stan

%%%%%%%%%%%%

This sentence's length and the use of a mark create an unexpected blank line
below for some reason..... \mark{mark}

Removing one period after ``reason'', or the space before the mark, makes
the blank line disappear. (I'm not saying that putting a space there makes
sense.) Does anyone know why this happens? My only guess is that the mark
prevents the space before it from being removed when TeX breaks the text
into lines. I'm not sure if this is a bug, but it seems odd, at least.

\bye

your conjecture is correct -- the \mark
*does* inhibit removal of the space, and
that is forced to the next line, which
remains empty in the output.  you should
also get an "underfull hbox 10000" in
the log.

not a bug.  just one of the idiosyncracies
of the tex design,
-- bb
```