Thank you for that.
If you need more info try Googling "GBAS" or "LAAS".
I did that and Wikied it too.
Now I know all about USA's WAAS (Wide Area Augmentation System) and LAAS (Local Area Augmentation System) and Australia's GBAS (Ground Based Augmentation) and GRAS (Ground based Regional Augmentation System.)
Japan and Europe are also developing their own systems. Fantastic stuff!
Wikipedia WAAS:
http://en.wikipedia.org/wiki/WAAS
Wikipedia LAAS:
http://en.wikipedia.org/wiki/Local_A...ntation_System
http://www.airservicesaustralia.com/...S_brochure.pdf