-: b Binary backward compatibility; has an exported Perl_ implementation
-: but function is also normally a macro (i.e. has the "m" flag as well).
-: Backcompat functions ("b") can be anywhere, but if they are also
-: macros ("m") then they have no proto.h entries so must either be in
-: mathoms.c to get marked EXTERN_C (and skipped for -DNO_MATHOMS builds)
-: or else will require special attention to ensure they are marked
-: EXTERN_C (and then won't be automatically skipped for -DNO_MATHOMS
-: builds).
+: b Binary backward compatibility. This is used for functions which are
+: kept only to not have to change legacy applications that call them. If
+: there are no such legacy applications in a Perl installation for all
+: functions flagged with this, the installation can run Configure with the
+: -Accflags='-DNO_MATHOMS' parameter to not even compile them. If there
+: is a macro form of this function that provides equivalent functionality
+: (using a different implementation), also specify the 'm' flag. The 'b'
+: functions are normally moved to mathoms.c, but if circumstances dictate
+: otherwise, they can be anywhere, provided the whole function is wrapped
+: with
+: #ifndef NO_MATHOMS
+: ...
+: #endif