David, As Mr Suzuki says, despite the U prefix, USAT is not a Unicode source character. The reason why a solitary USAT source reference has suddenly popped up in Ext. B is that several thousand ideographs were proposed for encoding by SAT in what will be CJK Ext. F in Unicode 10.0 next year (there are currently 2,884 USAT characters in Ext. F). At the WG2 meeting in Matsue Japan last year, in response to UK ballot comments, USAT-00061 was unified with U+20991 in Ext. B (see http://www.unicode.org/wg2/docs/n4701-M64-Recommendations.pdf Recommendation M64.05c). I suppose that the Unicode Standard will be updated with a description of SAT when Ext. F is included in v. 10 next year.
Andrew On 28 June 2016 at 06:09, drmccreedy . <drmccre...@gmail.com> wrote: > I see one codepoint now has the kIRG_USource property value of "USAT" in the > Unihan_IRGSources.txt file from Unihan.zip: > U+20991 kIRG_USource USAT-00061 > > UAX #45 (U-source Ideographs, > http://www.unicode.org/reports/tr45/index.html) mentions UTC and UCI but not > USAT. > > UAX #38 (Unicode Han Database, http://www.unicode.org/reports/tr38/) updated > the syntax for the kIRG_USource property (but not the description) to > U(TC|CI|SAT)-[0-9]{5} so I'm pretty sure it's not a typo. > > Where can I find a description of the USAT value? > > Thanks, > > David McCreedy