Most RNAV approaches have the notations:

"GPS or RNP - 0.3 required", and
"DME/DME RNP - 0.3 not authorized"

1. The "or RNP .3" seems to imply some navigation unit other than gps
can have rnp .3 Any idea what?

2. If an FMS with rnp .3 is able to conduct this approach, wouldn't
it need a gps input to be that accurate? Surely IRS with dme updating
can't be used for any non prec approach?

2. Any approaches where dme/dme rnp .3 IS authorized?

Stan