Re: Weird in-line trivial EQN issue with 1.22.4 - bad font number

[Tadziu Hoffmann]

It's an issue with eqn material inside a macro definition.
To avoid expanding eqn-generated escapes at macro definition
time, bracket the macro definition with ".ec #" (or some other
unused character) and ".ec" (to restore backslash as the escape
character after the macro definition).  This way, backslashes
are retained in the macro and escapes are only evaluated at
macro expansion time.