CMIFeedback related question

Hello community,

I am a developer and I am trying to persist scorm interactions with my comany's LMS (I've built its scorm 1.2 API myself several years ago) and I need some advice regarding CMIFeedback format.

More specifically, I have a Quizmaker 2.0 SCO, with a question like this:

What is your favor color?

- red

- green 

- blue

I noticed that when a cmi.interactions.n.student_response is being set (or a cmi.interactions.n.correct_responses.m.pattern), quizmaker first tries to set the actual value (for example, 'red') and if that fails with 405, it then sets the proper 'r' - since, per the SCORM 1.2 CMIFeedback documentation, this value must be a single letter (for type 'choice')

However, I'd like to deviate from the SCORM protocol myself and accept the 'red' as a valid answer, show I can then print a report. So my question is:

The SCORM protocol clearly states that for CMIFeedback 'choice', valid values are  a single letter (or a list of comma-separated single letters), in the range a-z0-9. If I were to use Articulate's attempt of setting the CMIFeedback to an actual word, what is the correct regular expression to use (in other words, what are the possible values that Quizmaker might throw at me, so I can create a suitable regular expression)?

Thank you in advance.