AA's fare code chart (linked HERE) shows a percentage mileage earned based on fare code with the note "AAdvantage status member bonuses will be applied in addition to the percentages shown for base miles."

As far as I can tell, every flight I've been on this year has earned LPs based on the spend only. All have credited LPs as expected and RDMs are seemingly equivalent to the LPs. I've definitely booked some of the lower earning fares (V, G, Q, etc) and not noticed anything strange. For example, as Platinum at the moment, even a Q or O fare booked at $400 earns me the expected 400 * 8 = 3,200 LP and 3,200 RDM.

So what exactly is this percentage and when / where does it come into play with the new Loyalty Points structure?