HP-41C service module question

[Ángel Martin]

It looks like there are many more unanswered questions than available answers... I only knew of the existence of the following diagnostics ROMS:

1. ET-11966, for the 41C/CV - includes Card Reader tests
2. Service Module 0004160937 - for the CV/CX . No Card Reader tests.
3. ET-14048 HP-IL Diagnostics ROM
4. ET-11968 82143A Printer Service ROM

Never heard of the flag-wired or the "Port Extender I/O" counterpart though.
Either a red herring or a real myth? We'll probably never know...