Below are the 2 responses I got to my question from other news groups. Though I should share them with you.
Oracle RDB was DEC (Digital Equipment Corporation) RDB before Oracle bought
Provisions were made Oracle was not allowed to drop it.
Sybrand Bakker, Oracle DBA
FWIW, I attended an Rdb Admin course less than a year after Oracle had
bought Rdb. The instructor said that the Oracle "suits" who had done
the deal had expected to be able to eventually merge the two products,
but after the deal was done and the engineers finally got a chance to
look at it, they discovered the two products were too internally
dissimilar to be able to provide any effective migration/merge path.
Oracle did manage to dramatically increase maintenance contract fees
on Rdb. The company I worked for at the time (and still work *at*, on
someone else's payroll) was paying DEC a few thousand per year for
maintenance. When Oracle bought it, maintenance went to tens of
thousands per year.
(Opinions expressed do not necessarily represent those of my employer.)