Sorry, I am probably wrong in regards to MS SQL Server and nVarchar. I don't have an MS source.

I was thinking of unicode and the term 'multibyte' rather than double-byte.

Unicode (specifically the UTF-8 subset) can be encoded in 8-bit 'octets' and there can be between 1 and 4 of them (according to the 2003 revision).

See page 3 of the internet RFC 3629

http://www.ietf.org/rfc/rfc3629.txt

Off topic sorry.