Engineering defaults to "use" skills are errata?

[Captain Joy]

GURPS often breaks things up into design, repair, use skills (p. B190). Notice also that all Electronics Operation skills default to Electronics Repair (same)-5 or Engineering (Electronics)-5. Notice that all Electronics Repair skills default to Electronics Operation (same)-3 or Engineering (Electronics)-3. Notice that almost all Engineering skills default to Electronics Repair (same)-6 or Mechanic (same)-6. This all makes perfect sense.

Why do the Engineering specialties: Parachronic Psychotronics, and Temporal default to Electronics Operation (same)-6? I mean, the Electronics Repair skills exist for those specialties, so why not base the Engineering defaults off them? This has to be errata, right?

[Kromm]

It's not errata – it's remaining true to the original Third Edition source text. If you dislike it, feel free to change it. As it stands, the way specialty x works is independent of they way specialty y works. Granted, the source of that oddity here is more "author fiat" than anything else – I suspect that the writers in question wanted heroes to be able to use and invent such gear, but not easily fix it if they end up stranded in the astral plane, a parallel universe, or another time. That creates an adventure wherein the PCs have to take weeks to find local tech or cobble together a replacement, not just spend a few hours with a wrench. I do agree that an Electronics Repair default would be more consistent, though, with an Electronics Operation default being an option for certain kinds of campaigns.