Usilr tech level scale different from equipment?

[Paladin852]

The Usilr scale in Atow rates planets' technological sophistication A-F, with A being highest tech.
The Technology rating of items is A-F, with A being the lowest tech.

The Equipped trait check in Atow companion says you get +2 to the check for each letter code the planet's technological sophistication exceeds the item's.
If I'm on a sophistication B planet trying to acquire a tech C item, what's the modifier?

[skiltao]

I haven't played AToW, but I suspect that would be a +2 modifier to your roll.

USILR - Item
   A - F
   B - D
   C - C
   D - B
   F - A

[Paladin852]

That's my intuition, but it also doesn't address E-tech items (I suppose you would make up a fictional E rating for planetary sophistication, but that changes most of the chart) and I was kind of hoping there was an errata or something somewhere I hadn't been able to find.

[skiltao]

I forgot about E. I guess that would make it a +4 modifier, then.

USILR - Item
   A - F
   B - E
   C - D
   D - C
 n/a? - B
   F - A

I don't follow AToW errata, so I'll have to let someone else field that.