I am attempting to locate the authority source for the term "marcorg" as used in the following:

Example 1: Institution only

<physicalLocation authority=”marcorg”>MH</physicalLocation>
This "marcorg" apparently refers to:

Source Codes for Organizations

marcorg - MARC Code List for Organizations. Online:

But can someone help us with an authority query relating to marcorg, please?

Although I see authority=marcorg in several MODS and LCWA pages/documents on the LOC site, I have been unable to locate an authority list that includes "marcorg" specifically.

How can I confirm that "marcorg" is an authority term and where can I locate this?

(p.s. this has nothing to do with the -- mid american regional council -- acronym)

Many thanks