The flash memory of the PIC controllers is the program memory where code is stored. You can initialize the variable at compile time and it will be written together with the program code.
To write to the program memory by the running program you need to execute special instructions. For the PIC 32 see section 5. Flash Programming[^ PDF] of the PIC32 Family Reference Manual.
A compiler or assembler may provide functions or macros to perform the writing or compilers may have built-in support for writing. So the answer if the value is written depends on the used compiler. But if the compiler does not support writing to flash memory, you will get an error at compile time.
it really depends on the company/implementation - I doubt there's any 'standard' meaning, eg 'Example', 'Extension' - the only way to know for sure is a side-by-side comparison using [insert name of your favourite diff/compare tool here]