Each special orders included a number of paragraphs or lines which dealt with a particular subject. Unfortunately I don't have access to the entire set, just parts of them. For instance, here's pp. XIII of S.O. 283 and pp. XXVI of S.O. 252 --
SPECIAL ORDERS No. 283, ADJT. AND INSP. GENERAL'S OFFICE, Richmond, November 28, 1863.
* * * * * * XIII. Brigadier-General Clingman will proceed with his brigade without delay to North Carolina and replace Brigadier-General Ransom's brigade at Goldsborough and Weldon. The latter brigade, on being relieved, will proceed to Petersburg, Va., and report to Major-General Pickett. Brigadier-General Barton will forthwith proceed with his brigade to Hanover Junction, and hold himself subject to the orders of General Lee. * * * * * * *By command of the Secretary of War: JNO. WITHERS, Assistant Adjutant-General
SPECIAL ORDERS No. 252, ADJT. AND INSP. GENERAL'S OFFICE, Richmond, Va., October 23, 1863.
* * * * * * * XXVI. The execution of the conscript laws will be suspended in the following named counties in the State of Georgia until otherwise ordered: Rabun, Towns, Habersham, White, Lumpkin, Dawson, Gilmer, Fannin, and Union. * * * * * * *By command of the Secretary of War: JNO. WITHERS, Assistant Adjutant-General.
Without having the entire order, it won't be possible to know what specific part of it put either Hughes or Kimbrough into the army.
I don't anything in the service file for BTC which mentions "line marker" or anything like it. Where did you find it? Can you reference a specific document?