RDS - AIP ERSA RDS (this may be a little bit Australian if you are in another country)
AIP - Aeronautical Information Publication (the normal means by which a State publishes how it complies with its operational responsibilities, declares non-compliance with ICAO requirements, and is the basic source of routine information for pilots when going about their flying activities.
ERSA - Enroute Supplement Australia. Provides a majority of cockpit level information relating to flights around Australia and is an essential adjunct to flight planning and operation
RDS - Runway Distance Supplement to ERSA. Provides information relating to aerodrome runways, especially distances and obstacle clear surface slopes for takeoff.
PAMC - Provisional Acceptable Means of Compliance. The PAMC referred to started the idea of pre-planned segmented takeoff climb performance for large aircraft. Long time since I have seen anything to do with it. If not the first to comply with this, one of the earliest recertifications was the F27 and this all happened a LONG time ago when I were still a lad in grey school knickers. Just think historical antecedent to FAR/JAR 25.
Climb - gross is the reasonable minimum gradient you should see in the real world OEI situation - provided the aircraft is flown reasonably well. The gross to net margin is a notional fudge factor to provide some margin for this and that - but doesn't consider turbulence or inversions which are a worry if you are out in such conditions and one quits on you. I wouldn't worry too much about fleet averages and the like - that's certification backroom stuff from previous eras. You might find some useful gen in the
FAA Flight Test Guide.
It certainly is not impossible to see an aircraft down in climb somewhere near the certification net performance ... but you are having a REAL BAD hair day if you are faced with that circumstance.
The OEM does the work ... then they have to sell the certification product to the regulatory authority to get the Type Certificate.