L2/05-227 Source: Eric Muller Title: Draft Letter to ISO regarding Ideographic Variation Sequences Date: August 20, 2005 As described in the Unicode liaison report for WG Meeting #46 in Xiamen, the UTC approved a project of developing a Unicode Technical Standard to establish a registry of variation sequences for Ideographic characters. Such variation sequences can be used to reference specific variants of ideographs. The UTC recognizes that the needs of various user communities for such variation sequences cannot be accommodated by a single, unified collection of sequences. The purpose of the registry is to ensure that multiple collections can coexist without compromising the interchangeability of texts using them. A proposed draft of this standard (UTS #37) has been posted for public review following the UTC 103/L2 200 meeting (May 2005). After incorporation of the review feedback, this standard has been advanced to the draft stage at the UTC 104/L2 201 meeting (August 2005). That document is available at . To permit the use of the sequences registered under the auspices of UTS #37 in conformance with ISO 10646, we propose to modify the second and third paragraphs following note 1 in clause 20.4 from: No sequences using characters from VARIATION SELECTOR-2 to VARIATION SELECTOR-16 from the Basic Multilingual Plane and VARIATION SELECTOR-17 to VARIATION SELECTOR-256 from the Supplementary Special-purpose Plane are defined at this time. All the allowed sequences using variation selectors are defined in this clause; all other such sequences are undefined. Furthermore, no sequences containing variation selectors and a mix of combining characters or composite characters will be defined. to: The allowed sequences using variation selectors are those defined in this clause, as well as those registered according to Unicode Technical Standard #37; all other such sequences are undefined. Furthermore, no sequences containing variation selectors and a mix of combining characters or composite characters will be defined. Sequences registered according to UTS #37 are constrained to be composed of a unified ideograph as the base character and one of VARIATION SELECTOR-17 to VARIATION SELECTOR-256 from the Supplementary special purpose Plane; no such sequence shall be defined by this clause. No other sequences using characters from VARIATION SELECTOR-2 to VARIATION SELECTOR-16 from the Basic Multilingual Plane and VARIATION SELECTOR-17 to VARIATION SELECTOR-256 from the Supplementary Special-purpose Plane are defined at this time. (This base text is that of Amendment 1; Amendment 2 does not modify clause 20.4.) We would welcome the inclusion of this change at the earliest available opportunity (such as a possible Amendment 3), as the establishment of the registry would greatly improve the integration of the UCS in existing publishing industry practices and processes. ---