<font face="Verdana, Arial, Helvetica, sans-serif" size="2">Originally posted by nerd:
The non-Ted fare classes are there to provide the correct inventory for itineraries that include non-Ted segments.</font>
Yup, so while there may be zero inventory in Y on say DEN-PHX, there could be Y inventory on STL-PHX via DEN. I don't think passengers can actually buy a Y fare from DEN-PHX on the Ted non-stop.
Don't know anything about the E's counting for additional EQM. I'd love that though!