What is the purpose of the VEXcode drivetrain command?

Can anyone explain the purpose and parameter definitions for the drivetrain command in VEXcode V5 Text?

JPearman gives a good explanation of the drivetrain in VexCode V5 Text in this post. Read through it and it should help.

that thread should still be valid, just bear in mind that the drivetrain class changed a little between that preview version and VEXcode 0.9 and will change a little more in 1.0 once it is released.