what the prefix means in different engine families of GE waukesha.ATGL,APG,VHP,VGF,VSG,275 GL

[namihabib]

I need to know about what the prefix means in different engine families of GE waukesha. There are 6 that I came across: ATGL,APG,VHP,VGF,VSG,275 GL. I searched the internet to find only two:
VHP = Very High Power
APG= Advanced Power Generator.
Need to know about the others as I have to give a presentation

 

[enginesrus]

I think VGF variable gaseous fuel, its just a guess. It would be a good idea to just call them and ask.