Make terminology consistent regarding observation of change and expressing

[moorepants]

We say things like:

"the velocity of P in A means the change of a vector from a point fixed in A to point P possibly moving in A when observed from A"

"velocity of P with respect to A"

"express velocity of P in A"

I think we need to consistently use "when observed from" to characterize the derivative when observed from a frame and that "with respect to" should probably not be used for this because I think I may also use it for expressing a vector in the unit vectors of a frame.