IANA instructions about sub-registries created by MT-PRIORITY extension need to be clarified

[aamelnikov]

Donald Eastlake wrote:

Section 8.3, item (9): Appears to have an open technical question that should be resolved.

draft-ietf-emailcore-rfc5321bis-32 now contains the following text:

(9) // Following paragraph requires input from Alexey, revised text, and // WG signoff on the result. Another subregistry question arises with the MT-PRIORITY extension. The authors of RFC 6710 (one of whom is obviously quite handy) should review how that extension is handled, including whether the use of "MT- PRIORITY" in some places as "PRIORITY" in others is confusing. At present, it is listed as a Service Extension, in the Extension Parameters list, and with its own separate registry in the Mail Parameters registry group [60] [57]. At least that registry should be shown as a sub-subregistry of the Service Extensions Registry and/or carefully cross-referenced.

[aamelnikov]

Speaking as one of the editors of RFC 6710, I think the only change needed is to rename "SMTP PRIORITY extension Priority Assignment Policy" sub-registry to "SMTP MT-PRIORITY extension Priority Assignment Policy".