This information is from defind.c, version 3, of 3 June 1991.

The following tokens are predefined by the preprocessor/compiler for
VAX 11/780, BSD 4.3:
                    unix (1)
                     vax (1)

The following tokens are defined when <sys/param.h> is included:
                     BSD (43)
                  BSD4_3 (1)
                    unix (1)
                     vax (1)

Additionally, the following standard tokens are defined:
                __FILE__ (defind.c)
                __LINE__ (5506)
