Form D Control System (DCS) rules apply only where designated by which of the following?

• A. Timetable, Bulletin Order, or Form D line 6
• B. Form D line 2 authority
• C. Non-signaled DCS rules substituted for ABS
• D. The line 2 authority is fulfilled

Answer: (A)

DCS rules aren’t in effect everywhere; they apply only in sections that official documents designate. That designation comes from the timetable, a bulletin order, or the DCS information shown on Form D line 6. When you’re on the road, you check those sources to know if DCS applies to the track you’re on. If there’s no designation in those documents, DCS does not apply and you follow the standard rules in force for that line, such as ABS. The other options don’t establish where DCS is in effect: a Form D line 2 authority isn’t the standard designation for DCS applicability, substituting non-signaled DCS for ABS concerns when DCS can be used, and line 2 authority being fulfilled doesn’t specify where DCS applies.