User defined format letters & numbers (Writer)

Hello folks

I’m creating a form in LibreOffice Writer using the form controls. For a couple of the controls I created some user defined formats to make sure the fields format as needed. For example: For the telephone # field I entered (000) 000-0000 so if someone entered in 5557771234 it formats as (555) 777-1234. I’m trying to do the same thing for a field that contains letters and numbers.

I’m in Canada and our postal code is formatted as letternumberletter numberletternumber in uppercase (ex: A1A 1A1). In a similar fashion to the telephone # example, if someone typed in a1a1a1 I want it to format as A1A 1A1. I tried some of the excel placeholders that I came across like @#@ #@# but it doesn’t work. Is this possible to do? I did this by right clicking on the form field then selecting “Control” and then scrolling down to “Formatting” and selecting “User-defined”.

Or, can this be done in Calc? I will try to do something in there if it’s easier.

Thanks.

Do you only want to view the input in upper case or do you want to change the characters?