Can anyine help me? I believe there is an ISO standard encoding where 4 bit
values are encoded as 7 bits known as 'ISO 5'. I checked ISO references and
ISO 5 is about photographic material quality. So I guess this ISO 5 is a short
hand refernece within another ISO standard.

The encoded message appears to be of regular length and always starts with
0x07 followed by 0x20, or 0x1F, or 0x1E. Looking at the bit patterns bit 7 is
sometimes set (i.e. value >= 0x80), and parity varies from byte to byte.

Any ideas or clues? Could it be something like Intel Hex?
Thanks in advance,
Mike