For Blu-ray Discs, there are three regions, designated as follows:
Region A: U.S., Japan, Latin America, East Asia (except China).
Region B: Europe, Africa, Australia, New Zealand
Region C: China, Russia, India, Remaining countries.
HD-DVD had indicated the possibility of, but never announced a specific Region Coding for its format. As a result, HD-DVD disc titles were never region coded.
In addition, regardless of the Region Coding question, the consumer also needs to take into consideration the technical differences between various television and video systems.
While North America, Japan, and Latin America employ an NTSC-based 30 Frames-per-second video system, most of the rest of the world is employs a PAL-based system with 25 frames-per-second. In addition, some of the other technical standards in use for audio processing and video processing could vary.
This means that an HD-DVD disc, even though not region coded, from another part of the World, may not necessarily play on a North American HD-DVD player or vice versa, but many do.