eventpass.asm allows the player to pass through the block when a certain number of events have been triggered.
eventscroll.asm allows the camera to scroll when a certain number of events is passed.
If you are going to use both, I recommend reading my recommendations for where to place these blocks. These blocks combined can create the perfect 'one screen where you must do something to continue' effect.
Also - this is my first block! :D Enjoy, and credit isn't necessary.