What does this list block do?

[bombmanyeeted]

I was looking at the append block and realized it had a relabel option. It had this block:

What exactly does it do, since it reported this when I tried seeing what it did:

[bh]

You'd have understood it if you used different values in the two inputs:

;~)

[warped_wart_wars]

That block is actually meant for 7.4 but Jens forgot to remove the Relabel option on APPEND when he made the 7.3.1 emergency update.

Anyway, it gives all the combinations of the inputs. A combination is a particular one selected from the first, then a particular one selected from the second, etc.