Additional 90 days after re-entry?

Hi! I've got an X2 visa issued in Shanghai, which was offered to us students so as to have an additional entry for China. It says Entry(s): 01 (yi), valid until Jan 31st. There is a remark saying: "Permitted to stay until 31 JAN 2015 for this time, and to stay for 90 days each time since the next entry" No stamps or crosses have been made yet.

I now booked flights in and out of HK in January. I just want to make sure, since there has been some confusion among the foreign students: Can I get back into China and stay for 90 more days with this (that is until end of March)? (Another interpretation of this remark would have been: I can leave China and come back for maximum 90 days, but all before Jan. 31st)

Thank you in advance for your help!