The June issue of BYTE magazine has a fairly long article on XENIX by Microsoft's XENIX product manager. Mostly, it's a standard "What's a UNIX" paper, but it also describes some of the enhancements they are adding to V7. The most important is support; additionally, they are going to add a fair amount of hardware error recovery (bad block handling, parity and power fail interrupts, etc.), as well as record handling, shared data segments, synchronous writing, improved interprocess communications, networking, and languages: Pascal, BASIC, FORTRAN, and COBOL.

You CAN'T in general assume people can go look at the source to figure out what an error means. Aside from the obvious fact that there are lots of users who don't speak C, recall that to get Unix a (non-Bell) site has to sign in blood a promise not to give out the sources to anyone. Many sites (especially University Computer Centers, who don't trust their users) protect /usr/src. (I know of one comp ctr at an unnamed major university in Berkeley that doesn't even make df suid because "It's none of your business if the disks are full". Since they also overbook disk quotas, which they have, this is a fun place to try to get any work done.) An even worse case is typified by Onyx, Microsoft, and other turnkey Unix system sources who don't let you have ANY sources. This is how a small business can afford to buy Unix - to not pay for a full source license. These poor guys can't go look at the source, and I can't tell you how many times I've wished I could in order to pinpoint some bug.