What values can I use in the InputMask Plugin?

I want to use the InputMask field on a textfield for a phone number. I managed to figure out that the character "9" allows digits.

What are the other characters that can be used here?

If I want to allow "(999) 999-9999" followed by an optional combination and any length of characters (e.g. "" or " extension 1234" or "5678", etc). How would I do that?

Please answer this for me too as a support customer. I cannot find documentation.

Hello!

You can use the following mask symbols:
"9": "[0-9]"
"a": "[A-Za-z]"
"*": "[A-Za-z0-9]

Moreover, you can add own mask symbols: https://examples2.ext.net/#/Form/TextField/InputMask/