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><ACRONYM
CLASS="ACRONYM"
>ASCII</ACRONYM
> and its 8-bit cousins are on the way out, and with them the assumption that a character can be represented by a single byte.  The new kid on the block is <A
HREF="http://www.unicode.org/"
TARGET="_top"
>Unicode</A
>, similar to but not precisely the same as ISO 10646.  Unicode (despite its name) is a set of standards.  The most widely implemented is the 16-bit form, called UCS-2.  As you might guess, UCS-2 uses two bytes per character, allowing it to encode most characters of most languages.  Because <SPAN
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>"most"</SPAN
> is far from <SPAN
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><I
CLASS="EMPHASIS"
>all</I
></SPAN
>, there are nascent 32-bit forms, too, but they are neither complete nor in common use.</P
><P
>In the same sense that 7-bit <ACRONYM
CLASS="ACRONYM"
>ASCII</ACRONYM
> was extended to 8 bits, Unicode extends the most prevalent <SPAN
CLASS="QUOTE"
>"8-bit <ACRONYM
CLASS="ACRONYM"
>ASCII</ACRONYM
>"</SPAN
>,  <ACRONYM
CLASS="ACRONYM"
>ISO 8859-1</ACRONYM
>, to 16 and 32 bits.  The first 256 values remain in Unicode as in <ACRONYM
CLASS="ACRONYM"
>ISO 8859-1</ACRONYM
>: 65 is still <TT
CLASS="LITERAL"
>A</TT
>, except instead of being 8 bits (0x40), it's 16 bits (0x0040).  Unlike the 8-bit extensions, Unicode has a unique 1:1 map of numbers to characters, so no language context or <SPAN
CLASS="QUOTE"
>"character set"</SPAN
> name is needed to decode a Unicode string.</P
><P
>UCS-2 is the system employed by Microsoft NT-based systems.  Microsoft database servers store UCS-2 strings in <SPAN
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>nchar</SPAN
> and <SPAN
CLASS="TYPE"
>nvarchar</SPAN
> datatypes.  Microsoft also designed version 7.0 (and up) of the <ACRONYM
CLASS="ACRONYM"
>TDS</ACRONYM
> protocol around UCS-2: all metadata (table names and such) are encoded according to UCS-2 on the wire.</P
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