Here is a basic list of issues to be specified: 

1.     Types of doors: interior solid or hollow core

2.     Model name from the catalog or website and its finish colour

3.     Door size or rough opening sizes. Total purchased doors quantity and sizes

4.     Configurations (single or double / swing, bypass, pocket etc.)

5.     Types of hardware needed (lockset and handles? concealed or plain bearing hinges?)

6.     Swing directions (LHI /RHI / LHO / RHO)

7.     Additional options: smart sweep, metal strips, frameless system etc.

8.     Project lead time (when are the doors needed at the job site?)

9.     Budget

10.  Any special requirements (fire ratings, etc.)