In "The LaTeX3 Sources" document it says (on p. 296,
"Older versions of expl3 divided up primitives by “source”:
that becomes very tricky with multiple parallel engine
developments, so has been dropped. To cover the transition,
we provide the older names here for a limited period (until
the end of019)."
Does this mean one should avoid using functions such as
If yes, are there any alternative to such commands?
Furthermore, in "The expl3 package and LaTeX3 programming"
document it says (on page 7, Released 2018-12-12):
"D This means: Do not use. This special case is used for TEX
primitives. Programmers outside the kernel team should not use
Again, which function should a programmer who is not a member
of kernel team use instead of "\etex_iffontchar:D"?