What does M mean in the Entries field?
M stands for multiple: unlimited entries during the visa's validity. A visa showing 1 or 2 allows only that many crossings into mainland China, after which it is finished regardless of the Enter Before date.
When does my 60-day stay clock start?
On the day you enter, as recorded on your entry stamp — not on the day the visa was issued and not on the day you booked. The days are calendar days, and the exit day is part of the count.
Can I renew a used-up visa inside China?
No. New visas are issued only by Chinese embassies, consulates and visa centres outside China. Inside the country you can only extend an L visa once by up to 30 days, or apply for certain residence permits.
My visa expires next month but I have entries left. Can I still enter?
Yes, on or before the Enter Before date. Your stay then runs its own Duration of Each Stay from that entry, and the visa simply cannot be used for any further entry afterwards.
How do the three fields interact with a Hong Kong reset?
A reset to Hong Kong or Macao restarts the Duration of Each Stay on your next entry, but it still spends one entry if your visa shows 1 or 2. Only M-entry visas can be reset indefinitely.