ASCII characters are the most commonly known non-Unicode characters. English language characters are often included in the first 128 code points (Hex 00-9F) in non-Unicode code pages. However, in the popular Japanese ShiftJIS character set, many of the first 128 code points are reserved as lead bytes and are not available for English characters.

In SQL Server 2000, the non-Unicode character data types are char, varchar, and text. These data types use the character representation scheme defined in single or double-byte code pages in SQL Server.