Validation mask for TextField question

Targets macOS
1

Is it possible to construct the validation mask so that, in certain parts, will accept an arbitrary number of alphanumeric characters?

For example:

Any number of characters, followed by and underscore, followed by two digits followed by a lower case letter?

The mask: _##>? takes care of the last bit but how can I allow there to be an arbitrary string of characters before the underscore? (if that’s possible at all.)

2

Use a backslash begore the characters of the string

\m\y_##>?

I got this from:
https://documentation.xojo.com/api/text/format.html