The sets in the Modified Legal Format are the sets you are allowed to play with in tournaments and Leagues. This is the Brittish Modified Legal Format from now to the Nationals: by the worlds Legends Awakened will be allowed.
Set Name
Ex Holon Phantoms (HP)
Ex Crystal Guardians (CG)
Ex Dragon Frontier (DF)
Ex Power Keepers (PK)
DP I: Diamond & Pearl (DP)
DP II: Mysterious Treasures (MT)
DP III: Secret Wonders (SW)
DP IV: Great Encounters (GE)
DP V: Majestic Dawn (MD)
Black * Promos 37 - 41
DP Promos DP01+
DP Trainer Kit (TK)
POP 4
POP 5
POP 6
POP 7
New POPs...
This format is called HP-on.
Look here for updates...