Bruce,
I posted some brief definitions from SIS yesterday to Bryan.  I believe he
will post them soon.  In the mean time the latest Standards I am aware of
are from 1992:  36CFR Part 68 in July 12, 1995 Federal Register (Vol. 60,
No. 133).  "The Secretary of the Interior's Standards for the Treatment of
Historic Properties.  These Standards are also used by the IRS for those
seeking federal tax benefits for work on certified historic properties.  I
am sure if you call your local IRS agent he can give you a copy and explain
the Standards.  Right......
Leland