I believe the numbers on this front card indicate the index card numbers assigned to the document from which information was obtained to input to the individual card in his file.
January 1865 "In confinement at Houston"
February 7, 1865 "Prisoner" Department of Trans Miss. Dist. of Tex. New Mex. & Ariz. Title of record: L. R.
April 1865 "Absent without leave"
I do not know what the 'L. R.' stands for, but it is my understanding that the District of Texas, New Mexico and Arizona was the Western Sub-District of the Trans-Mississippi Department, C. S. A.
Therefore, based on the fact that he was recorded on the February 7, 1865 Regimental Return as "In confinement at Houston," I would believe that he was under arrest, reason unknown, but perhaps shown on the document referenced which would be found at the National Archives in Washington, DC.