When using th function get_data(), one of the parameters is field which can consist of different values depending on the time of data you are retrieving. This field has itself some parameter such as SDate, Period as it can be seen in this example:

data, err = ek.get_data(['AAPL.O','MSFT.O'], ['TR.ROEPercentTrailing12M(SDate=0D,Period=FI0)'])

Where could I find an exaustive list of the different such fields. When trying out some field in the excel API i always come accross "CH=Fd RH=IN" in teh formula but I have no clue whetehr it is excel specific or also a parameter I should include when use PYTHON API.