The minimum information to be recorded is specified in the data set (20 items) required by WHO, it is available in http://www.who.int/ictrp/network/trds/es/index.html. [1]
The additional information requested by RPCEC serves specific purposes of registration. For further information, see page RPCEC trial registration Data Set [2]
Links:
[1] http://www.who.int/ictrp/network/trds/es/index.html
[2] https://rpcec.sld.cu/en/requested-data