Intermediate clue
Also known in the clue library as Conditional (If not … then …).
Two questions matter more than the pattern itself: does this clue give you everything now, or only later — and does it become a mark on the board, or a note you have to keep separately?
This one fires on an elimination, not a confirmation. Easy to miss, since most solvers only watch for the trigger becoming true.
Keep it as a written rule until the trigger is ruled out.
Reading the clue is half the job. These are the methods that turn it into board progress.
Reading a conditional clue backwards: if the consequence is false, the trigger must be false too.
Firing a conditional clue: forward when its trigger becomes true, backward (see Contrapositive Reading) when its consequence becomes false.
Writing down a fact the clue gives you that has nowhere to go on the board yet.
See this clue type on a live board, or go back and browse the rest of the library.