China entity problem in FAO

[semio]

Some background:

in FAOSTAT, there are two entities for China:

Country Code	Country	M49 Code	ISO3 Code
351	China	156*	CPR**
41	China Mainland	128	CHN

* 156 belongs CHN china in M49 Code
** CPR is not an official ISO alpha-3 code

We asked FAO and confirmed "China", m49 156 is all of china, what normally would be called CHN

The problem:

FAO releases their (forest) land use statistics only for complete China (mainland + hk,macao,twn). Other stats they have separated. How strict are we on geo chn in Gapminder namespace? Is gapminder geo chn China mainland? WB and UNpop use CHN as china mainland ("for statistical purposes"). Other sources aren't clear. How data providers normally handle this case? Is there any unwritten rule?