Can someone explain this?

[Paps]

Interesting thread! I normally hang in the Double Bass area, but lutherie is interesting.
Both points of view are correct. This a semantics issue and Stevensivak is using the more precise definition.
A piece of wood is either book-matched or not, but as every piece of wood has 2 sides, only one side can be an exact match.
Even though the other sides are not as close a match, the piece of wood is still a book-matched piece of wood.
IE, one side of a book matched slab is a book-match, the other side of a book-matched slab is not!
So, when we realise this is a small, trivial difference in perspective and everyone is correct, we can relax!

 

[stevensivak]

So now that we all agree, is i possible that the body in question is actually book matched as opposed to being slip matched? The front, from what we can see, is very "mirror-like" the back, not so much...

 

[Beej]

This is really going around, haha.

Logs can be sawn in creative ways, but when you saw a trunk into flitches, you have what's called a boule. Some of us buy or make boules for building purposes. It's basically a stack of boards all cut from the same tree in stacked consecutively cut order. The thickness of the boards will range on what the sawyer or customer wants.

Any pair of boards will have bookmatched faces on one side but when you turn them over they will be slipmatched at best. The exception is the board from the middle of the log, which theoretically has straight grain in all angles and may look nearly identical when flipped back and forth. 'Bookmatched' conventionally means the pair of faces that are cut from one another and form a near mirror image. When I saw a log, I make and store bookmatched sets, which are the faces sawn from one another. The backs may be close, but oftentimes are not close enough to appear bookmatched. The bookmatched term refers to the two faces rather than the boards.