I recommend putting the array and accessor function in a separate source file of your own. Then you can #include the .h file in pin_isr.c protected area. I'll raise your question - whether you *should* be able to put the declarations in the pin_isr.h file - with the development team though.
Thanks for the fast reply.
I will put the array/accessors in an separate source file. It'd be interesting to hear what the dev team think.