Trend worktop jig

Hello all, I have just bought a trend kwj700. I hope I'm just being thick, but why are the pins numbered? I have 3 pins with a number one on, these fit snugly in every hole. 2 number 4 pins and 1 number 2 pins, these go in each hole but require some force, so much that I do not want to completely insert them.

Is this a fault? Or am I being dopey.

Thanks for your time