The 1997 UBC
refers to 1991 NDS (National Design Specification for Wood Construction of the
American Forest and Paper Association). See Part 1 right
before section 2316.
Good luck finding
There is a more current NDS printed in 1997
(there may be even more current than that - 1999?). It has all the
design and section values you need. The NDS separates larger "timbers"
into a "beams and stringers" category and a "posts and timbers"
category. The difference being the section's aspect