Another library expansion. This time it’s Microsoft C 4.0 documentation (1986)—because it’s not available online, is not easy to find offline, and because Jeff asked for it.
MS C 4.0 was an early Microsoft compiler, implementing first glimpses of the not-yet finalized ANSI C standard. It was released in summer 1986 and superseded first by the little-known Microsoft C 5.0 in 1987, and more importantly by the very popular Microsoft C 5.1 in early 1988.
An important addition in version 4.0 was CodeView, a full-screen source level debugger which superseded DEBUG and SYMDEB. 30 years ago, source level debuggers were fancy!