It sounds to me like you are getting a generic 'C' formatting error.

Since these are stored in the code space you may need to define them as:

const code char refstr[]{};

I haven't had to do this for a while so I can't remember exactly how it is formatted, I just get my Kernigen/Richey book out then if that doesn't work I go the the compilers manual to find out where they stray from the standards.

HTH
Dave Miller