I am reading a book "Practical Electronics for Inventors" and I was trying to understand the FETs, at several places the author has mentioned about the trans conductance that he has noted with gm. I did understood what transconductance(gm)is but I [took this datasheet for a reference](https://www.fairchildsemi.com/datasheets/2N/2N3819.pdf) to figure out if that is a static parameter or a parameter that depends upon various other parameters.In the datasheet there is a mention of Forward Transfer Conductance(gfs) & Output Conductance(goss). Which one is the Transconductance(gm), and what does the other conductance mean.