Yes, you are correct. If a locomotive, or any rolling stock does not have a subsidiary abbreviation displayed somewhere on it, then it belongs to the SOUTHERN proper. On freight cars and cabooses, these letters are usually on the upper right hand side.
Of course, all of this is primarily for financial and tax purposes, otherwise, it's all owned or operated by the Southern Railway Company.
Now, in "modern day" times, through paper mergers within mergers and such, you don't see these "sub-lettering" any more.
Hope this helps a little.
On Sun, Jan 24, 2021 at 8:41 PM, Michael Shirey
Ok guys, I understand the check codes and reporting marks on the side of a locomotive cab. What if a locomotive does now have a reporting mark for ownership. Is it just assumed it belongs to SOU? I ask this because there seems to be a few GP38-2 with no marks. I have Athearn #40609 SOU 5025 GP38-2.
PCRRHS and SRHA Member