Rank in China
China uses the same system as Japanese. It goes from kyuu (ji) to dan (duan). There are official testing services where one can take a test from 9 j to 1 ji then from 1 duan to 5 duan. After testing, a certificate is awarded.
Chinese amateur ratings usually go to 5 dan until they win tournaments, after which they can get 6 dan ratings and above. Usually the number of 6-dan certificates awarded per tournament is limited to a maximum of three. However, often fewer than this are given out as you need to finish in the top 12 and these positions are often all occupied by 6-dan+ players. 7-dan is awarded for winning certain national tournaments and 8-dan is an honorary rank for winning the World Amateur Go Championship. Currently China has a dozen or so 7-8dan amateurs and several hundred 6-dan amateurs.
Because of the above restrictions and the fierce competition, Chinese 4 dan amateurs will still be very strong players, in comparable fashion of the Korean 1 kyus. Due to the slow response time to personal improvement and tournament results, even among 5 dan players the strength can vary up to 4 stones.
Most Chinese players do not mention or even know their rank. Many mainland Chinese players only "play for fun" and never bothered to get their strength assessed. It often turns out that a random unranked player from China who steps into some Go club has a strength of a strong 4 dan.
In Taipei people usually know their approximate ranks, probably because of having significant access to the internet.