The draft says, "High-level protocols could implement desired result though the use of using tailoring."
This paragraph is liable to be wrong.
Within a closed system, such as a document is generated by Microsoft Office, every document is read/edited within single /same application. Tailoring of the default data table works with ease in a single application.
But as for the open system, for example such an application of publishing documents by EPUB. Creator application and reader application is different ones. In the case of the creator of EPUB documents would tailor the default data table, could the reader application understand the tailored data table? How you could exchange the tailored information?
Actually, it will be quite difficult to operate "the tailoring of data table". Tailoring will not work. As a result, every open system will be forced to heavily depend on the default table of UTR#50.
As I said in the other thread, many western origin letters and symbols may take upright and sideways depending on the style and context. The single default data table would be an obstacle for effective interchange of Japanese vertical writing document in the open system. Two default tables such as SVO table and MVO table will be necessary.
Antenna House, Inc.