Question: How do you attach two boards for a door frame?
Option 0: After shaping tongues and grooves on the wood, place some wood glue into the groove of the receiving board and slide the tongue board into it.  Bind the wood together so it dries tight with clamps.
Option 1: After shaping tongues and grooves on the wood, place the groove of the receiving board and slide the tongue board into it.  Drive nails into the wood to hold it together until satisfied.
Answer: 0