New Member - Civil War Envelope?

Hello. I am new to this site and very happy to have found it. I have looked through several threads and haven't found an answer to my question. I have attached an envelope (which I LOVE) from the civil war. It is from the Assistant Adjutant General's Office (Samuel Breck) to Brevet Luit. Col. James R. Gilmore. (pen name Edmond Kirke).

My question is about the lower left corner. Any idea what the numbers and letters mean?

Thank you in advance for any insight.
AQM was Assistant Quartermaster and that was the position that Gilmore had in the army. He was from Pennsylvania and served in the Quartermaster’s Department from Nov 1864 to Nov 1866.
 
Back
Top