Alan is correct. Tartan "short hose" of the 17th and 18th centuries were sewn up from woven cloth, not knitted, with the seam running up the back of the leg. The fabric was described in one period source as being "of a thicker stuff than their plaids are made of." So perhaps different weights of tartan were woven for different uses!

They could either be full-footed or of a footless type (these are easy to make):



I think the latter type was used by poorer folk who ran around bare-footed quite often. I also think "moggan" is a modern term....