this is how they work
Region code 0 Informal term meaning "worldwide". Region 0 is not an official setting; discs that bear the region 0 symbol either have no flag set or have region 1–6 flags set.
region1 Bermuda, Canada, Cayman Islands, United States and U.S. territories
region 2 European Union, Albania, Andorra, Bahrain, Bosnia and Herzegovina, Croatia, Egypt, Faroe Islands, French Guiana, Georgia, Greenland, Guernsey, Iceland, Iran, Iraq, Isle of Man, Israel, Japan, Jersey, Jordan, Kosovo, Kuwait, Lebanon, Lesotho, Liechtenstein, Macedonia, Moldova, Monaco, Montenegro, Norway, Oman, Qatar, San Marino, Saudi Arabia, Serbia, South Africa, Swaziland, Switzerland, Syria, Turkey, United Arab Emirates, Vatican City State, Yemen
region 3 Southeast Asia, Hong Kong, Macau, South Korea, Taiwan
region4 Caribbean, Central America, Oceania, South America (except French Guiana), Mexico
region 5 African countries not explicitly included in other regions, Indian subcontinent, countries included in the former Soviet Union, Belarus, Mongolia, North Korea
region 6 People's Republic of China (except Macau and Hong Kong)
region 7 Reserved for future use (found in use on protected screener copies of MPAA-related DVDs and "media copies" of pre-releases in Asia)
region 8 International venues such as aircraft, cruise ships, etc.[1] ALL Region ALL discs have all 8 flags set, allowing the disc to be played in any locale on any player.