Comparison shortcuts for string content?

I'm trying to validate some input on an Excel form.

I want to ensure that people input HEX or BIN only. Is this some that can be done in a single IF statement? Comparing a multi-character string to an inclusive list? OR, do I have to loop through each individual character of the string and do a comparison?

I know there's shortcuts in ACCESS? (Or so it would seem with my searches)

Thanks for the help!

you could test if the string converts to a valid hex or binary value, otherwise i believe you would have to test each character, there are functions in the vb6 codebank that would do the conversion for binary
alternatively you could automate access from excel and pass the values for testing