What are the differences between \mskip and \mkern? The TeXbook writes the following (ch. 18): You can insert math glue into any formula just by giving the command ‘\mskip⟨muglue⟩’. [...] ...
Let's say I have a variable, which may - or may NOT - be a number; how can I handle the cases when it isn't a number, without crashing with "! Missing number, treated as zero." ? In practical terms, ...
I wonder how costly it is in terms of compilations speed and also other terms like memory etc., to store some content in a box and use this box then afterwards only once (or maybe twice). Is the ...