Mill-grading - Werkssortierung

I came across this term in a brochure and am relying on the company's information that it is the correct translation. Can anyone out there provide a definition for "mill-grading" or "Werkssortierung"? The internet hasn't been too helpful. Is grading in this case an evaluation of the quality and quantity of planks each tree provides? "Sortierung" does point that way. No hurry, I just think that this in an interesting term and want to understand it.

Well, from what I understand Mill-grading is more to do with the quality of the wood, and what the lumber is certified to be used for.
Check out this Link, it might give you a bit better idea.

I think it refers to quality, at least if I'm reading the information in this link correctly: Lumber mill worker job description.

Lots of interesting terminology there (for me at least, since I know very little on the subject) - bull chain operators, headsaw crews, seasoning green lumber... I certainly learned something this morning!

Exactly, Kay.
To which I might add "Ahnendielen", translated as "abbey", referring to boards treated to be used-looking with prominent knots and a slightly uneven surface.
EDIT: @ Mook - your link didn't work for me.