Mike,

From what I've gathered S.O. stands for Special Order.

One of my relatives has a record similar to the one you posted, he was detailed March 1, 1863 by S.O. 54/2, Dept. & Army of Tenn --Bragg.

Another of his records indicate he was detached as a Shoe Maker by S.O. 44 dated March 5, 1863, he spent the latter part of the war "pegging shoes" in Columbus, GA.

Perhaps someone here could advise exactly where these records can be found.

Mitchell