Multiscript Design Notes

Availability

In the "experimental" folder on Sourceforge forge for both biblatex and biber. Both at version 4.

LANGID is an override for the language of the fields in an entry (at least when the biber "msstrict" is enabled). What to do about LANGIDOPTS field?
"sortlocale" option should be output in the .bcf as BCP47 ideally. No clean way of doing this currently
babel shorthands are not activating in the \namepart<part><msform><mslang> and \listitem<msform><mslang> auto-created macros currently. Something to do with these being defined in the preamble but this is not obvious. They are being created in \blx@bblend currently. Not critical but nice to have.
Currently using hard-coded BCP47<->babel/polyglossia/biblatex language identifier rules. Users can override the BCP47-> direction if needed. This all needs replacing with a proper BCP47<->langid mapping package to insulate us from babel/polyglossia variations as it doesn't help if polyglossia supports BCP47 but babel doesn't.