All data should be used as a guide only not a specification.
Plain weave means the warp and fill threads pass over one thread then under the next.
This is the most common weave. This is a more pliable than the plain weave consequently easier to form around curves. 8HS Satin weave means the fill thread passes over 7 warp threads and then under one. This weave is also very pliable and excellent for compound curves. The warp thread runs the length of the bolt.