@JasperHabicht so annoying when people delete questions mid-answer:

\documentclass{article}
\usepackage{amsmath}
\usepackage{stackengine}
\begin{document}
\[
    \xrightarrow
    [
      \substack
      {
        \def\stackalignment{l}
        \stackunder{This is some text.}{This is some more text.}
      }
    ]
    {}
\]
\end{document}

@cfr I bought Kopka and Daly and TLC2 when I first started LaTeX (~2004) - I was a research assistant so on a reasonable but not great amount - but yes I was not a student

@cfr Partly mindset - I bought a book on Lua to learn, and I'm currently re-reading one on Python - I expect to learn stuff from books :)

@JosephWright no, really, it is not mindset.

@cfr The question is back it seems.

@cfr ??

@cfr I mean that I'd not even consider trying to learn LaTeX or any other programming language without at least using one book - maybe from a library, but certainly would want something on dead trees

Is this the state-of-the-art method for implementing a switch-case structure? tex.stackexchange.com/a/386283/127473

Since each department at my university has different guidelines regarding margin settings and line spacing, I would like to execute different commands based on the department specified in the preamble.

@EmanueleNardi \str_case:nnTF, yes. Take a look at interface3.pdf.

So Herbert provided a super fast fix for dejavu-otf, though for my class I can have users on OverLeaf. Is there a way to hook into a package in order to execute code if the version date is younger than a certain date?

@daleif Depending on the package and the patch, you can simply patch a package within a project. In particular, if only the .sty file needs a patch, you can simply upload the new file into the project, and it will be used instead of the installed version.

@yo' I'm providing a class for other employees to use (and they can use OverLeaf, this rewrite is specifically to make it easier for them), I just do not like distributing a copy of someone elses package. Or ask uses to manually update a package in OverLeaf because overleaf does not update pacdkages (for good reason).

Though here dejavu-otf with the usefilenames options will not work on OL currently either.

BTW: when can a Type 1 font safely be loaded by lualatex? Do we need a TU reencoding?

I think I'll just let the package fail, and provide an manual injection fix via a class option.

@daleif Yeah, got it.

Again regarding dejavu-otf, I can see that Herbert sets \mathversion{normal} and if I test using \blindmathpaper (from blindtext), I keep getting errors on \mathrm. MWE in 2min

\documentclass[a4paper]{article}
\usepackage[usefilenames]{dejavu-otf}
\usepackage{blindtext}
\begin{document}

\blindmathpaper

\end{document}

Doesn't unicode-math remap those? I find all this \sym... stuff very confusing to users .

Ahh, mess with unicode-math in advance.

@JosephWright I did too, around the same time. TLC was very helpful.

@EmanueleNardi more or less, although you don't need xparse package in recent latex releases

@UlrikeFischer You said in a comment that that header setup of mine is "quite curious". Would you mind elaborating a bit? Would setting up "a suitable header definition" avoid that equality test, or just move it somewhere else?

Working on github.com/josephwright/siunitx/issues/732 ... I have of course found some issues in other places I have to fix first :)

@gusbrs I wouldn't do such tests in the \mark command but only when I build the header.

@egreg ^^ I will add Steinmetz notation support to siunitx at least :)

@UlrikeFischer With fancyhdr or something of the sort? How would you do that "vanilla"? Isn't that the business of the document class?

@UlrikeFischer Btw, regression tests are passing for the ltproperties approach. That's good enough for me. :-)

@JosephWright ^^ I found a place/way to set those. :-)

@gusbrs Do tell

@gusbrs My plan is to provide a generalised phase function - but first I spot some tidying up to do in angle handling more generally

@JosephWright tex.stackexchange.com/a/732046/105447. Indirect, but it's working.

@JosephWright I'm afraid I don't know what a "generalised phase function" would be...

@gusbrs Don't worry, it's my problem :)

@JosephWright Well, if you think it might be useful for that use case, please keep me posted.

Btw, I'm still in the process, but regression tests are already passing. And I think I'll be able to simply ditch a sizeable chunk of the package, and one of the parts which had originally been most difficult to get working right, with a simple straightforward application of ltmarks. And functionality is not only not compromised but improved. I'm not sure if he appreciates this kind of comment but, if someone here thinks he does, please send a big hat tip for FMi on that account. :-)

@JosephWright 💪

@egreg May take a couple of days - have spotted some tricky stuff I'd overlooked before

@JosephWright should I write something up for github.com/latex3/latex3/issues/1626#issuecomment-2512035236?

@DavidCarlisle I think it's not fair to put your name on the English translation here github.com/learnlatex/learnlatex.github.io/issues/… we need to correct all teh spelling errors :P

@Skillmon Please

@JosephWright you might close the issue now :)

@Skillmon the bits you wrote are probably not very reliable, but we take the blame rather than blame you

@DavidCarlisle that's a relief :)