Custom validation code for product ID and identification

I am looking for help with creating validation for a custom code that will be alpha numeric. Multiple choice question with 3 repsonse allowing text entry is currently being used, but a side-by side with 3 text entry options is another question type we looked at. Their will be three codes will be unique for each for each respondent and they will be a combinations of letters and numbers that identify the session, product and variety that the respondent is testing.

For example, a code might look like 1A.1.1A.11A

first set, 22 possible coded, 1 or 2 A-K
2nd set codes 1-9
3rd set 1-34
4th set A-D
5th set TBD, but also some combination of numbers or letters)

Each piece of the code means something different and we'ld also like to tie that to some embedded data for later classification

How do I create validation that would check to ensure that the code is being entered correctly? Do periods work if entered to separate the codes?

HELP!