Suppose you want your application to run in French. The application will be used in France and data will be displayed using the WE8ISO8895P1 character set. You would set NLS_LANG as follows:
NLS_LANG=French_France.WE8ISO8895P1
Now, suppose you still want your application to run in French, but this time
it will be used in Switzerland. You would set NLS_LANG as follows:
NLS_LANG=French_Switzerland.WE8ISO8895P1
More examples:
NLS_LANG=Norwegian_Norway.NDK7DEC
NLS_LANG=Norwegian_Norway.WE8ISO8895P1
NLS_LANG=Japanese_Japan.JA16SJIS
NLS_LANG=Arabic_Egypt.AR8MSWIN1256
NLS_LANG=American_America.AR8MSWIN1256
NLS_LANG=American_America.WE8ISO8859P1