The constructors for the Encoding API interfaces TextDecoder and TextDecoderStream can be passed an optional label argument, which identifies the encoding to be used.

The following table lists all encoding labels that user agents must support, along with the encoding that the label identifies. Note that most encodings have more than one label.

Label	Encoding
"unicode-1-1-utf-8", "utf-8", "utf8"	"utf-8"
"866", "cp866", "csibm866", "ibm866"	ibm866
"csisolatin2", "iso-8859-2", "iso-ir-101", "iso8859-2", "iso88592", "iso_8859-2", "iso_8859-2:1987", "l2", "latin2"	iso-8859-2
"csisolatin3", "iso-8859-3", "iso-ir-109", "iso8859-3", "iso88593", "iso_8859-3", "iso_8859-3:1988", "l3", "latin3"	iso-8859-3
"csisolatin4", "iso-8859-4", "iso-ir-110", "iso8859-4", "iso88594", "iso_8859-4", "iso_8859-4:1988", "l4", "latin4"	iso-8859-4
"csisolatincyrillic", "cyrillic", "iso-8859-5", "iso-ir-144", "iso88595", "iso_8859-5", "iso_8859-5:1988"	iso-8859-5
"arabic", "asmo-708", "csiso88596e", "csiso88596i", "csisolatinarabic", "ecma-114", "iso-8859-6", "iso-8859-6-e", "iso-8859-6-i", "iso-ir-127", "iso8859-6", "iso88596", "iso_8859-6", "iso_8859-6:1987"	iso-8859-6
"csisolatingreek", "ecma-118", "elot_928", "greek", "greek8", "iso-8859-7", "iso-ir-126", "iso8859-7", "iso88597", "iso_8859-7", "iso_8859-7:1987", "sun_eu_greek"	iso-8859-7
"csiso88598e", "csisolatinhebrew", "hebrew", "iso-8859-8", "iso-8859-8-e", "iso-ir-138", "iso8859-8", "iso88598", "iso_8859-8", "iso_8859-8:1988", "visual"	iso-8859-8
"csiso88598i", "iso-8859-8-i", "logical"	iso-8859-8i
"csisolatin6", "iso-8859-10", "iso-ir-157", "iso8859-10", "iso885910", "l6", "latin6"	iso-8859-10
"iso-8859-13", "iso8859-13", "iso885913"	iso-8859-13
"iso-8859-14", "iso8859-14", "iso885914"	iso-8859-14
"csisolatin9", "iso-8859-15", "iso8859-15", "iso885915", "l9", "latin9"	iso-8859-15
"iso-8859-16"	iso-8859-16
"cskoi8r", "koi", "koi8", "koi8-r", "koi8_r"	koi8-r
"koi8-u"	koi8-u
"csmacintosh", "mac", "macintosh", "x-mac-roman"	macintosh
"dos-874", "iso-8859-11", "iso8859-11", "iso885911", "tis-620", "windows-874"	windows-874
"cp1250", "windows-1250", "x-cp1250"	windows-1250
"cp1251", "windows-1251", "x-cp1251"	windows-1251
"ansi_x3.4-1968", "ascii", "cp1252", "cp819", "csisolatin1", "ibm819", "iso-8859-1", "iso-ir-100", "iso8859-1", "iso88591", "iso_8859-1", "iso_8859-1:1987", "l1", "latin1", "us-ascii", "windows-1252", "x-cp1252"	windows-1252
"cp1253", "windows-1253", "x-cp1253"	windows-1253
"cp1254", "csisolatin5", "iso-8859-9", "iso-ir-148", "iso8859-9", "iso88599", "iso_8859-9", "iso_8859-9:1989", "l5", "latin5", "windows-1254", "x-cp1254"	windows-1254
"cp1255", "windows-1255", "x-cp1255"	windows-1255
"cp1256", "windows-1256", "x-cp1256"	windows-1256
"cp1257", "windows-1257", "x-cp1257"	windows-1257
"cp1258", "windows-1258", "x-cp1258"	windows-1258
"x-mac-cyrillic", "x-mac-ukrainian"	x-mac-cyrillic
"chinese", "csgb2312", "csiso58gb231280", "gb2312", "gb_2312", "gb_2312-80", "gbk", "iso-ir-58", "x-gbk"	gbk
"gb18030"	gb18030
"hz-gb-2312"	hz-gb-2312
"big5", "big5-hkscs", "cn-big5", "csbig5", "x-x-big5"	big5
"cseucpkdfmtjapanese", "euc-jp", "x-euc-jp"	euc-jp
"csiso2022jp", "iso-2022-jp"	iso-2022-jp
"csshiftjis", "ms_kanji", "shift-jis", "shift_jis", "sjis", "windows-31j", "x-sjis"	shift-jis
"cseuckr", "csksc56011987", "euc-kr", "iso-ir-149", "korean", "ks_c_5601-1987", "ks_c_5601-1989", "ksc5601", "ksc_5601", "windows-949"	euc-kr
"csiso2022kr", "iso-2022-kr"	iso-2022-kr
"utf-16be"	utf-16be
"utf-16", "utf-16le"	utf-16le
"x-user-defined"	"x-user-defined"
"iso-2022-cn", "iso-2022-cn-ext"	"replacement"