I understand \romannumeralk when k is positive. However, I have seen \romannumeral0 in a few codes but I do not understand its use. What is it?
Example:
\romannumeral0\expandafter\xintzapspaces\expandafter{\MAT_tmpa};!;%
this is line 28 of the code of the section ROW REDUCTION (INITIAL) ANSWER of this post
\expandedis more powerful, but\romannumeralexpansion may have its uses nonetheless. – egreg Dec 29 '21 at 15:56\romannumeral0is not safe, better would be\romannumeral\^^@` instead, otherwise you might have issues with digits following the 0. – Skillmon Dec 29 '21 at 18:02