(U+6619): Add `<-denotational@usage' for BUCS+66C7; apply new
conventions for glyph granularity.
(U+6653): Add `<-denotational@usage' for BUCS+66C9; apply new
conventions for glyph granularity.
(U+6681): Add `<-denotational@usage' for BUCS+66C9.
(U+66C7): Add `<-denotational@usage' for BUCS+66C7; apply new
conventions for glyph granularity.
(U+66C9): Add `<-denotational@usage' for BUCS+66C9; apply new
conventions for glyph granularity.
(BUCS+66C7): New abstract node; unify A2-DJT-04621.
(BUCS+66C9): New abstract node; unify A2-DJT-04623.