Taken from Glenda Todd's book on the First Alabama Cavalry, USA, here is his record verbatim: "Randolph, Simeon, Co. M, age 42, born Morgan Co., AL, farmer, EN 11/30/63, Camp Davies, MS, released on surgeon's certificate on incompetency before mustered in."
The EN stands for enrolled.Once postential soldiers enrolled and went to Camp Davies, which is a camp that was located a few miles south of Corinth, they were given physical examinations which they needed to pass before being mustered in.Apparently, Simeon had a physical infirmity that kept him from passing that physical.
A little background: The chief officer of the regiment's Company L, Captain Sanford Trammel,was court-martialed in early 1864 for allowing three men with physical problems to muster into his company.This was despite the fact that they had been declared fit by Dr. William H. Clutter, the regiment's assistant surgeon. This is testimony to the emphasis that was sometimes placed on the army's desire to accept men without pre-existing health issues.(But elsewhere in the Union army, many women posed as men and passed physicals that were so superficial that no one noticed.)