Passages - Economy Class mileage credit on SQ

I recently read in the Delta Air Lines Sky Miles newsletter that one can now earn miles in economy on SQ - but only 70% of the distance. However, mileage credit is not given if the fare is booked in the X, G and Q fare classes. Also, "Certain other fares are excluded."
Does anyone know what type of fares these X, G and Q tickets are? Thanks as always for your help ...

X, G and Q class economy class fares are normally used by wholesale consolidators for their group or sometimes tour-included fares. You shouldn't have to worry too much about getting your points!

Thanks for your help!

X is freely bookable, it is just like UA V or
LH W.