ISO 10646 is defined by ISO/IEC JTC1/SC2/WG2. ISO/IEC JTC1 is the Joint Technical Committee on Information Technology, which was formed by an agreement between the International Electrotechnical Commission (IEC) and the International Organization for Standardization (ISO). It is created to cover IT related standards in both the IEC and ISO. ISO/IEC JTC1/SC2 is the international standardization subcommittee for coded character sets. It is set up by ISO/IEC JTC1. There is a working group under SC2 called ISO/IEC JTC1/SC2/WG2. It is an international standardization working group for the coded character set UCS - the Universal Multiple-Octet Coded Character Set - ISO/IEC 10646. ISO/IEC JTC1/SC2/WG2/IRG, or IRG for short, is the Ideoraph Rapporteur Group to handle work related to ideographic characters in ISO 10646.

The Year 2000 version of ISO 10646, ISO/IEC 10646-1:2000, was released in October 2000 which includes 6,582 additional ideographic characters (in Extension A, see next paragraph) in addition to 20,902 ideographic characters already defined in ISO/IEC 10646-1:1993. All characters in the HKSCS which are not included in ISO 10646 already have been submitted to the IRG for inclusion in future releases of ISO 10646.

Ideograph character extensions to ISO/IEC 10646-1:1993 are carried out in phases, which referred to Extension A, Extension B, Extension C, and etc. Extension A, which contains 6,582 ideographic characters, was released in October 2000. Extension B is published in ISO/IEC 10646-2:2001 with ideographic characters mainly from Kang Xi Dictionary, Han Yu Da Zi Dian and Han Yu Da Ci Dian. Currently, the IRG is working on Extension C and publication date is yet to be determined.