That is the short form for saying "Standard spelling of Navajo, according to Robert Young and William Morgan's revised edition of the standard Navajo Grammar and Colloquial Dictionary published by the University of New Mexico Press of the University of New Mexico in Albuquerque in 1987" :) -- basically the Navajo language's Webster's or Oxford Dictionary.

Since you guys asked, it was here:

https://help.openstreetmap.org/questions/69455/navajo-names-wrong-but-padlocked?

By now, I figured out what do to, but it does take a while.

I was following the advice I was given at your helpdesk