This article is dedicated to people who want to contribute to FPC. If you want to contribute to FPC, but you don't know how and what, then have a look at the list of open tasks.
Changes which are likely to break existing code, must be documented here: User Changes Trunk
New FPC features (both new units and new compiler/language features) should be added to FPC New Features Trunk
Operating systems support policy
For operating systems, support in FPC runs until any extended support period for the OS runs out (+ say 1 or 2 years grace period if there are no major problems with that). After that non-intrusive patches are committed, but no guarantees.