USGS Benchmarks - "... AZ MK"

[Napier]

Many USGS benchmarks appear in pairs that are close together, one with a name like “ALBATROSS” and the other named “ALBATROSS AZ MK”. What is the significance of the “… AZ MK” version relative to the simple version?

Could it possibly be an “azimuth marker” one could sight over to establish bearing from the simple-name benchmark? Just a guess.

[Xema]

From this NGS PDF document:

AZ MK - Azimuth Mark: A marked point established in
connection with a triangulation (or traverse) station to
provide a starting azimuth for dependent surveys. Note, some
azimuth marks also were positioned and some have an
underground disk. The azimuth mark is usually a pre-stamped
survey disk, generally 1/4 to 2 miles from the horizontal
station.

[Napier]

That’s it! Thanks!

Very excellent link, by the way. I’m all over it.