Reviewing my Great Uncles death in WW1, I see the term "24 trans to S.O.S" in his Company Muster Roll. He served in the 6th Marine Regiment attached to the US Army 2nd Infantry Division, Third Battalion, 82nd Company (I Company for the Army).
Could this abbreviated term S.O.S. mean "Ship Off Shore"?
It occurs after an individual is wounded and is usually preceded by a date of transfer such as:
"24 trans to S.O.S."
the digits change by date of incident, but not the language.