It occurred to me that since there is very little overhead in the RSC file format, there is no reserved space for future expansion. Symbian changed the UID for version 2 sis files so that they would not be recognized as installation files by older versiona of the OS. I suspected that if rcomp always adds 1 to the index size it may be as a cruder version of the UID change.

Older versions of the Resource loading functions would fail on attempts to load the new modified RSC files. I modified a few RSC files and attempted to run the associated programs under the emulator. Even values at offset 0x2 bring up an error message regarding corrupt resources. So, apparently new versions of the Resource loading functions fail when attempting to load older RSC files.

I haven't yet verified this from the rcomp source.