What is the legal requirement for yielding right-of-way when exiting a box junction (marked with yellow criss-cross lines)?

1. You may enter the box junction at any time even if your exit is blocked
2. You must not enter the box junction unless your exit road or lane is clear so you can pass through without stopping
3. Box junctions are parking areas for motorcycles
4. You must stop inside the yellow box for 3 seconds before proceeding