>I don't think you have to do anything, but it just triggers on when you type the normal input. The highlighted portions are shown in alternating colors.

So, yellow means it validates OK I guess.

BTW, what would be your interpretation on:

([A-Za-z0-9-]{1,20})-([A-Za-z0-9]{1,12})
([A-Za-z0-9-]{1,20})-([A-Za-z0-9]{1,4})

If you would code it, for example, what would be the logic in place?

When I first looked at the first one, I thought this meant alphanumeric characters + a dash character in all characters from 1 to 20 MINUS alphanumeric only in the first 12 characters. Which means, the dash would have been accepted only from position 13th and up.

But, support gave me information that this means the dash is supported from position 2 and up.

I really do not know what to believe now.