1. No, it's not a nationwide law. I ride a lot and quite far and have never experienced this ridiculous and discriminatory policy and if I was subjected to such draconian measures well hell have no fury like... but I'd also likely have a 5-10L fuel can and simply fill it and then use that to fill the tank of my bike.

2. ? doesn't apply in any of the provinces I've ridden in. Just travelled through Zhejiang, Jiangxi, Fujian, Guangxi in the past month and never experienced this nor saw it.

3. DL = drivers license/licence

4. Blue book = is really a misnomer since it refers to the blue wallet 行驶证 vehicle license/licence that are issued by the 交警大队车辆管理所 traffic police and vehicle administration bureau. This is the one that should be produced when demanded by an authorised person.

Green book (FYI) = 车辆登记证书 vehicle registration certificate that are issued by the 交警大队车辆管理所 traffic police and vehicle administration bureau