make and RCS. was RCS and SCCS

[andrew at alice.UUCP]

the % style metarules come from stu feldman in a version of make that was
first released as the make for research unix, version 8.
it is also the style supported by mk.

as for the claim that gnu invented rule chaining, it is hard to believe.
i may have this wrong but i thought rule chaining simply meant doing
transitive closure over rules; if this is the case then mk has been doing
it for three years.