Distance Restriction: Quite a complex word, as with distance restriction, IR refer for different class!!
Yes, it depends on distance the train making along with demand/non-demand in several sector!!
Demand may create more room & so more booking options, which can be outcome of sharing quota or increasing reach of GEN Quota to many possible stations!! Like Punjab Mail
High demand in several sector...
more... too can seize booking option for other section, for maximum allocation!! Like Karnataka Ep, booking restriction from NDLS b4 BPL!!