removing the .IX macro from the ms package in 1.23 breaks old documents

[joerg van den hoff]

I was not aware of this change (not following groff development closely) and it took me quite a bit 
of time today to find the root course of why some newly compiled old documents of mine do not 
contain an index any more.

the reasoning in the release notes "This undocumented 4.2BSD ms extension was similarly undocumented 
by groff mm and ms. No documents applying it are attested." seems not to be sound:

1.
existence of that macro was sure not a secret and if it really was undocumented in the official 
docs, that could have been fixed instead of just deleting the functionality.

2.
regarding "no documents": well, maybe no "official" ones, but mine sure did and those of other users 
probably too. :).

I have now reimplemented the macro as a fix/workaround (it really was a one-line macro in the 
orignal ms package anyway, I guess) but my simple question: why was it deemed necessary to delete 
the macro in the first place. I cannot see any benefit from doing this (except ca. 3 LOC less) but 
it sure did cost me some lifetime today to find out what is going on ...

br/joerg


ps: yes, I know that IX is not a full fledged indexing facility and that there are superior 
solutions including makeindex. but it sure is easy and sufficient for many purposes.