[cvsnt] shared subprojects

[Elim Qiu]

Sorry ask basic questions.
Let's say I have projects A and B, and project C is a subproject of both A
and B.
Is there a way to put them in the repository so that
(1) check out A will also check out C inside of A
(2) ci changes of A will ci changes in C (if there are changes in C)
(3) from within either A or B, any changes of C can be picked up no matter
from where the changes of C is commited.

Some times I can avoid such issue by modify C so that it becomes a framework
or package. But some times I don't have clear idea to handle the project
layout issues.

Thanks for any inputs