The 'alter' URI Scheme for Dispatchable ~handle References

This document defines the alter URI scheme as a dispatchable reference syntax for ~handle identity references published under the DNS substrate defined in [MCPDNS]. An alter: URI binds a textual ~handle reference, with an optional surface path, to a resolution and verification procedure that retrieves the handle's envelope from the publishing zone, validates the envelope's signature chain, and dispatches the result to an operating-system URI handler. The scheme is provisionally registered under [MCPDNS] Section 11; this document is the full registration request per [RFC7595] Section 3. The scheme is provider-neutral, introduces no new cryptographic primitive, and reuses the resolution and verification procedures of [MCPDNS] without modification. The principal contribution is to give operating systems, browsers, chat clients, and command-line tools a single dispatch surface for handle-typed references so that clicking, typing, or scanning an alter: URI yields a verified handle resolution rather than a free-text string.