Returns the opaque Subject Identifier a client instance is told for a
person — per client or registered sector (pairwise_subjects.ts),
derived over their stable subject where there is one — and records it in
the reference store, with the client and sector, so that presenting it
back as user resolves for that client only (section 2.4.1).
Returns the opaque Subject Identifier a client instance is told for a person — per client or registered sector (
pairwise_subjects.ts), derived over their stable subject where there is one — and records it in the reference store, with the client and sector, so that presenting it back asuserresolves for that client only (section 2.4.1).