I’m now vaguely competent in troff, an arcane forty-year-old typesetting language with conceptual similarities to TeX, in which I used to be a minor expert. troff is surprisingly flexible once you get over the first hump in the learning curve, which mainly involves cryptic two-letter commands.
My competency grew after being assigned the task of rescuing a troff-encoded manual for an old programming language by converting it to an archival pdf. Once I figured out the basic mechanics of the conversion, my boss’s boss got tweakitis – nudge that table, fix that linebreak, add page numbers, etc. By now I’m ready to start writing troff macros.