[TUHS] practice of aliasing C compiler with occ?

We've been recovering a 1980s programming language implemented using a mix of Pascal and C that ran on 4.1 BSD on VAX. The Makefile distributed to around 20+ sites included these lines for the C compiler. CC= occ CFLAGS= -g It seems there was a (common?) practice of keeping around the old C compiler when updating a BSD system and occ was used to reference it. Anyone care to comment on this observation? was it specific to BSD-land? how was the aliasing effected, a side-by-side copy of the compiler pieces? As at 4.1 BSD the C compiler components were in /lib (Pascal though was in /usr/lib). # ls -l /lib total 467 -rwxr-xr-x 1 root 25600 Jul 9 1981 c2 -rwxr-xr-x 1 root 89088 Jul 9 1981 ccom -rwxr-xr-x 1 root 19456 Jul 9 1981 cpp -rwxr-xr-x 1 root 199 Mar 15 1981 crt0.o -rwxr-xr-x 1 root 40960 Jul 9 1981 f1 -rwxr-xr-x 1 root 62138 Jul 9 1981 libc.a -rwxr-xr-x 1 root 582 Mar 15 1981 mcrt0.o