In the early days, the boundary between "national railway" and "local railway" was very clear. The national railways was powered by alternating current while the local railways(subway) used direct current. The trains on national railways run on the left while the subway run on the right. However, with a variety of reasons, they have produced many kinds of fusioned "cross-border" lines or trains from technical point of view. There are also companies in cities, provinces or regions participating in the operation of CR network. It mainly includes Hong Kong Railway Company MTR, Guangdong Pearl River Delta Intercity Rail Transit Co., Ltd., Guangdong Intercity Railway Operation Co., Ltd., Chengdu Regional Railway Co., Ltd., Hunan Intercity Railway Co., Ltd., Henan Intercity Railway Co., Ltd., etc. This kind of route still implements the real-name system. Although their routes are usually operated independently and can be taken by using local public transport cards or apps, you can still purchase tickets through 12306 web page and app operated by CR. For example, the Chengdu-Dujiangyan Suburban Railway can use "Tianfutong App" operated by Chengdu; Beijing suburban lines S1, S5 and S6 can use "Yitongxing App" and a special real-name "T-Union" card, which can be used throughout China, but "T-Union" cards issued by other cities cannot be used on Beijing suburban railway lines S1, S5 and S6. Guangzhou-Qingyuan Intercity Railway is "T-union" supported, but additional registration is required. Urban railways in some cities are also operated by local companies, although trains run on CR lines.  They use their own independent ticketing systems separated by CR. You need to buy tickets at stations or use local public transportation cards before get into the station, such as Jinshan Line of Shanghai Rail Transit ("T-union" support), S2 Line of Beijing Suburban Railway ("T-union" support) and Taizhou(台州) Urban Railway. This kind of railways does not need to take the real-name system. In addition, it should be noted that there may be other CR trains and cross-line trains on these lines, and the entrances of the station might be different with the national railway mentioned above.