It's AC 120-12A. You can download it from FAA dot Gov. The FAA used to have a great word doc of frequently ask questions for part 61, 91, and 141. It gave their interpertations on many subjects. But it appears to have been removed from their website. In fact it looks like a lot reformating of information is going on on their website since I last had to search it.

Hope that helps. I know your DPE will be looking for you to respond with some knowledge of common carriage, holding out, and the activities listed under 119.1 (e) when he starts with Area of Operation I, Task A - Certificates and Documents, 1.a. ... and on and on...

Oops. I should read closer. I see rickair7777 has already given you the AC. And I agree - it should be one question and about 90 seconds max of conversation.