Following is a list of character sets along with their widths:
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1 Octet 8bit:
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Windows 125* (CP125*)
CP*
ANSI
ISO-8859-* (IEC-8859-*)
Macintosh (Mac OS Roman)
KOI8-U (potentially KOI*8-*)
KOI8-R
MIK
Cork (T1)
ISCII
VISCII


1 Octet 7bit:
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US-ASCII
K0I7

2 octets 16 bit:
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UCS-2
UTF-16* (UTF-16BE etc)

4-octets 32 bit:
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UCS-4
UTF-32

Variable-width:
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Big5 - http://en.wikipedia.org/wiki/Big5 (1-2 bytes: 00-7f=1, 81-fe=2)
HKSCS - http://en.wikipedia.org/wiki/HKSCS (a big5 variant, but some variants use 10646)
ISO-10646 (IEC-10646) - http://en.wikipedia.org/wiki/ISO_10646 (unicode)
UTF-8 (1-5 bytes)
ISO-2022 (IEC-2022) - http://en.wikipedia.org/wiki/ISO_2022
Shift-JIS - http://en.wikipedia.org/wiki/Shift-JIS

A good resource:
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http://en.wikipedia.org/wiki/Character_encoding#Simple_character_sets