DEFUN ("define-abbrev", Fdefine_abbrev, Sdefine_abbrev, 3, 6, 0,
doc: /* Define an abbrev in TABLE named NAME, to expand to EXPANSION and call HOOK.
-NAME must be a string.
+NAME must be a string, and should be lower-case.
EXPANSION should usually be a string.
To undefine an abbrev, define it with EXPANSION = nil.
If HOOK is non-nil, it should be a function of no arguments;