Relation between OpenVG API and VGU API

May I know what is the relation between OpenVG API and VGU API?Also, what is the different between this 2 set API?

The VGU library contains utility functions which may be useful to application developers using OpenVG. The intention is to restrict the OpenVG API to providing a good abstraction of plausible hardware features, and to move purely utility functionality out into a separate library.

Eben

It’s probably also worth mention, that generally VGU is completely implemented on top of OpenVG. So those implementations of VGU are completely platform independent.

Thanks for the useful info