Maxlength in F6 Forms

Hello,

I'm trying to setup a form in F6 and limit the number of characters that can be inputted. Also using Pi for the calculations.

I'm using the F6 number stack, within a form stack, and set the range to 0 - 99 (as below). This limit works if using the up/down arrows that appear next to the box but this won't stop a number beyond this range being typed in, i.e. 1321654689.

I have used the maxlength="n" in another web app to limit the number of characters that can be inputted in a form field. Any idea where I can set this attribute for individual F6 form inputs?

Sorry no URL at the moment because I can't publish this page publicly.

Thanks,

Paul