Many languages, such as English, Russian, Chinese, and Greek, have different characters in their alphabet. If English is the default language on your computer, the English character set contains only 255 different characters and can’t be used for Russian, Chinese, or Greek.
The NATIONAL CHARACTER set uses the code in two bytes of data for each character of the alphabet. This Unicode can encode up to about 4.3 billion characters (using UTF-32 encoding). The Unicode Consortium maintains the unicode standard. See www.unicode.org.

NATIONAL CHARACTER is the same as NATIONAL CHAR and NCHAR.

Example:    COL1 NATIONAL CHARACTER(20)

COL1 is a maximum of 20 double-byte characters in length.