On 2/16/2018 8:00 AM, Richard Wordingham via Unicode wrote:
A more portable solution for ideographs is to render an Ideographic Description Sequences (IDS) as approximations to the characters they describe. The Unicode Standard carefully does not prohibit so doing, and a similar scheme is being developed for blocks of Egyptian Hieroglyphs, and has been proposed for Mayan as well.
A point of clarification: The IDC's (ideographic description characters) are explicitly *not* format controls. They are visible graphic symbols that sit visibly in text. There is a specified syntax for stringing them together into sequences with ideographic characters and radicals to *suggest* a specific form of CJK (or other ideographic) character assembled from the pieces in a certain order -- but there is no implication that a generic text layout process *should* attempt to assemble that described character as a single glyph. IDC's are a *description* methodology. IDC's are General_Category=So.
The Egyptian quadrat controls, on the other hand, are full-fledged Unicode format controls. They do not just describe hieroglyphic quadrats -- they are intended to be implemented in text format software and OpenType fonts to actually construct and display fully-formed quadrats on the fly. They will be General_Category=Cf. Mayan will work in a similar manner, although the specification of the sign list and exact required set of format controls is not yet as mature as that for Egyptian.
--Ken
