The above hexadecimal set on 7-segment displays is probably as old as seven-segment displays themselves, and I am 100% sure HP folks knew about it; just chose to not use it. I was just surprised you seemed to be unaware of it, that's all.
So far, nobody noticed (commented on) the detail that HP's 7-seg symbol set on the HP 5004A has two zeros. Resulting in potential ambiguities. Probably not too serious for signature analysis, but still...
Did they do that just to save a few gates in the 4-bit to 7-seg decoder logic?
Another recent buy: HP 1670D. Cheap because of the broken knob, but it comes with the knob and appears to be a clean break of the shaft, ie can be glued.
Why? See my sig.
Incidentally, this may interest those doing HP LIF <--> PC DOS file interchange. The 1670D has HPIB, and quoting the programming manual:
The MMEMory (mass memory) subsystem commands provide access
to the disk drives. The HP 1670D-series logic analyzers support both
LIF (Logical Information Format) and DOS (Disk Operating System) formats.
The HP 1670D-series logic analyzers have two disk drives, a hard disk
drive and a flexible disk drive.