It's exactly similar to annotating today a Han text with notes in English. So I'm not sure it needs a specific encoding, as this may just be a shift from one script to another.
Of course the PARAGRAPHOS characters are to be encoded in the Supplemental Punctuation block where they can be used for many scripts. There's a FORKED PARAGRAPHOS though and a REVERSED FORKED PARAGRAPHOS though, which names may not be all that good if they can be used in a bidirectional context.
Ken? -- Michael Everson * * Everson Typography * * http://www.evertype.com
