New M visa multiple entry cummulative number of days stay per calendar year.

If I were to apply for a 2 year, multiple entry M, is the maximum cumulative days stayed in China still under 180 days (less than 6 months) like the former F policy? Or has the cumulative days for the M changed? Also, I would like to verify if I have a multiple entry, M, each entry duration should not exceed 30 days (or up to max 90 days if I apply for 2 extensions) per entry? Which means in each calendar year, I can come in and out as long as I do not exceed a total of 180 cumulative days? Thanks so much for your help.