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.
[2] While T.61 continues to be supported in modern versions of X.500 and X.509, it has been deprecated in favor of Unicode.
[4] The following table maps the T.61 characters to their equivalent Unicode code points.
They prefix the letters, as opposed to postfix used by Unicode.