After entering into 'expert' mode on the website and finding a flight
using the "search by schedule"

I see the following on "availibility"
F3 Y9 B9 M9 E9 U9 H9 Q9 V9 W9 S9 T9 K9 L9

I think this implies that it's quite empty, and there's a VERY high chance of being able to do a same-day standby on the flight

Am I correct?

More generally
If it says Y9 it means that there are 9 "or more" seats availble in that code.

Am I correct?