There is no such thing as "confirmed standby." Those terms are mutually exclusive, and thus oxymoronic.


Here are the actual terms, in reference to normal revenue public fare tickets:


Standby - available for free to AA elites/AAirpass/OW elites/military and premium/Y/B/H fares; prioritized by status, travel interruptions, and check-in time

vs.

Confirmed Flight Change (CFC) - available to all passengers for $75; first come, first served; based on E-class availability on the day of departure

More information here.