T.61 is an ITU-T recommendation for a Teletex character set. T.61 predated Unicode, and was the primary character set in ASN.1 used in early versions of X.500 and X.509 for encoding strings containing characters used in Western European languages. While T.61 continues to be supported in modern versions of X.500 and X.509, it has been deprecated in favor of Unicode. It is also called Code page 1036, CP1036, or IBM 01036.
While ASN.1 does see wide use and the T.61 character set is used on some standards using ASN.1 (for example in RSA Security's PKCS #9), the 1988-11 version of the T.61 standard itself was superseded by a never-published 1993-03 version; the 1993-03 version was withdrawn by the ITU-T. The 1988-11 version is still available.
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