I am trying to format a input box with a format like 'DD/MM/YYY'. Is there a way to restrict anything different from that?
what is the issue you are having? it would be better if you can share a sample in order to help you.
The only rare thing i see in your format is that you are using YYY instead of YYYY for year format.
I've tried an input box, in number tab selected date and DD/MM/YYYY and it worked fine!
Please let me know if this helps.