HDG TRACK DEV DURING SID DEP PROC.

Narrative

WORTH 5 DFW WAS ASSIGNED BY ATC ALONG WITH THE AMARILLO TRANSITION. THE 18L RWY WAS ASSIGNED FOR TKOF. THE SID CALLS FOR A '170 DEG HDG FOR VECTOR TO APPROPRIATE RTE.' TWR GAVE THIS CLRNC; 'CLRED FOR TKOF; FLY HDG 170 DEGS AND MAINTAIN 10000 FT.' THE HDG AND ALT ARE A REPEAT OF THE SID (SAME AS) AND LEAD TO THE 274 DEG RADIAL OFF DFW VORTAC (AMA TRANSITION). UPON INTERCEPT OF THE AMA TRANSITION RADIAL (274 DEG); I INFORMED THE CAPT THAT WE HAD INTERCEPTED OUR RTE AND SHOULD TURN TO A 274 DEG HDG TO TRACK. DURING THE TURN; DEP ASKED OUR HDG AND WHEN INFORMED THAT WE WERE TURNING TO INTERCEPT THE AMA TRANSITION; DEP INSTRUCTED US TO MAINTAIN A 170 DEG HDG WHICH WAS PROMPTLY DONE. IF NO HDG HAD BEEN GIVEN ALONG WITH THE TKOF CLRNC IT IS CLR THAT A 170 DEG HDG SHOULD BE MAINTAINED UNTIL 'A VECTOR TO APPROPRIATE RTE' IS ASSIGNED. IF THE WORD MAINTAIN HAD BEEN ISSUED WITH THE HDG (IE -- 'CLRED FOR TKOF MAINTAIN HDG 170') IT IS CLR TO HOLD A 170 DEG HDG. I UNDERSTOOD THE 'FLY 170 DEG HDG' AS OUR 'VECTOR TO APPROPRIATE RTE' AS STATED IN THE ASSIGNED SID.