Disclaimer: Always check your specific datasheet. "M522" may refer to different components across different manufacturers. When in doubt, measure twice, solder once.

In the maker community, "M522" is shorthand for a specific configuration of and Decay modes . If you look at the datasheet for many Polulu-style drivers, setting the MS1 and MS2 pins to specific states (High/Low) results in a truth table. The 522 usually refers to a 1/16 microstepping setting with a specific mixed decay ratio.

I recently rebuilt an old Anet A8 printer (a notoriously fire-prone machine) with M522-based drivers. The difference was night and day.