sentences:  They have been released officially in region 1 (Americas), region 2 (Europe & Middle East), region 3 (Korea), and region 4 (Oceania & South Pacific) formats.In addition to their region encoding, releases vary depending on the region in which they were released.In addition to standard single-season DVD box sets of the show, limited edition collectors' editions have been released that include all six seasons in one complete set.