SC2 WG2 Nxxxx

L2/12-087

Title: Proposed Changes to ISO/IEC 10646 Annex I Ideographic description characters
From: Unicode & US National Body
Date: February 9, 2012

ISO/IEC 10646 defines Ideographic Description Sequences (IDSes) in Annex I, and imposes two kinds of restrictions:

• the components can only be coded radicals or coded ideographs
• Note 2 limits the overall length of an IDS, and the distance between successive Ideographic Description Characters in an IDS

Those restrictions are actually problematic for two main users of IDSes, namely the IRG and the UTC. The IRG uses IDSes of existing and proposed characters, as a tool to detect potential unifications; those IDSes actually involve private use characters as components. Similarly, potential characters are tracked in UTR#45; for example, the IDS of the biáng character (see http://en.wikipedia.org/wiki/Bi%C3%A1ngbi%C3%A1ng_noodles) exceeds the overall limit.

The proposal is to modify annex I to:

• add private use characters to the list of possible components
• remove Note 2.

The UTC has already approved similar changes to The Unicode Standard.