41C ROMs: LBL linkages

[RobertM]

I'm trying to understand something in the 41C ROM format, particularly where it includes USER code.

I understand the ROM structure, and I know that UCODE areas of the ROM have a 2 word "prefix" that specifies (among other things) the number of regisers and how many bytes in the first register are required to copy the code from ROM to RAM.

Also, the LBL/END chain is calculated correctly for global labels and ENDs in the ROM ... except for the first LBL after a UCODE prefix. It appears that the first global LBL after a UCODE prefix can have any value for the bbbr rrrr rrrr values (hex C bbbr rrrr rrrr F nnnn kkkk ...).

PRINTER ROM, first label after first previx is LBL "PRPLOT", has "C8 00 ..." implying a 4 byte/0 register link.

PPCL ROM, first label after first prefix is LBL "MK", has "C6 00 ...", implying a 3 byte/0 register link.
PPCL ROM, first label after second prefix is LBL "LF", has a "C6 00 ...", also implying a 3 byte/0 register link.
PPCL.ROM, first label after third prefix is LBL "ML", has a "CA 00 ...", implying a 5 byte/0 register link.

Does anyone know the meaning of the first link values after a UCODE prefix in 41C ROMs?

Thanks,
-RobertM