Mass coefficient??
 

I am work on coal gasification, and i am trying to change the pyrolisis model that already exists in CFX. When i implement more than one products (apart from CH4, i add also H2,CO,CO2,H2O) and i choose the fuel analysis as an option and it doesn´t work. When I choose mass coefficient then everything run normally. Can someone explain me what is exctly this mass coefficient, because it doesn´t exist in Helpsection and i noticed that it is not necessary of the sum of mass coefficients of these 5 components to be equal to 1.

Thank in advance for helping!