John, all

My intention in using the work “transparent” was to indicate that all 256 EBCDIC characters are allowed including any kind of operand characters and comments plus continuation character and sequence characters up to 80 byte record length.  So yes the compression and decompression routines will need to handle any special byte codes used in compression which can also appear as valid byte codes in the original source.  This is the sort of compression and decompression routines required to handle any sort of data like ZIP does.