There really is no inconsistency. Firstly I'm not going into far25, so forget 25-7. (if you have a couple of years.... ) Vmc and Vmcg are as defined in far23. Vmca is as defined in the GAMMA spec for flight manuals which is referenced in 23-8 and has Clements and Gallagher's signature on it so it must be right. Somewhere along the line Vmcg has been added to the Gamma spec