I'm still going with what I wrote as it's what makes sense to me (whatever 156/159/169 says)![]()
Having Knowledges as subskills (or fractions) was how I saw it too until I noticed Grav. In preveous versions of Traveller, Grav was a skill in its own right. It didn't matter if you were over ground, over the sea, or in the air, it was all the same.
And remember, some Knowledges don't exist as part of ANY Skill. The sciences, world knowledge, career knowledge, etc. This further undermines the idea of Knowledges being subskills, though not conclusively.
So, yeah, we need Marc to explain and give us a ruling.