An input mask helps the user with the input by ensuring a predefined format. This can be useful for dates, numerics, phone numbers etc. Input mask functionality is available for the editbox and text area in the 'Validate' properties.
What’s the difference of input masks and validation rules?
input masks are about formatting; validation rules are about correctness of values.
Note: there is no direct link between validation and input mask, so you wil need to make sure that the combination masking and validation makes sense
The drop-down menu includes several predefined masks, but you can also enter custom masks.
This feature uses Inputmask by Robin Herbots: https://github.com/RobinHerbots/Inputmask