What is 1st NAND Flash Device and 2nd NAND Flash Device?

Hello Friends,
I am using RCM3365 core. While I am reading the Dynamic C function Reference Manual, I am seeing some API Routine applicable for First NAND Flash Device and Second NAND Flash Device. Example: WriteFlash2() .

            In RCM3365 which one is First and Second NAND Flash Device. Please Can anybody give the answer for this question?