]> Alter Meridian Pty Ltd

blake@truealter.com

This document defines the alter URI scheme as a dispatchable reference syntax for ~handle identity references published under the DNS substrate defined in . An alter: URI binds a textual ~handle reference 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 reference may be scoped to an organisation, narrowed to a named facet of the identity, and addressed to a typed action surface. The scheme is the addressing form of the ~handle@org:facet/action reference; its resolution semantics are those of , reused without modification. The scheme is provider-neutral, introduces no new cryptographic primitive, and reuses the resolution and verification procedures of without modification. The principal contribution is a single, self-verifying dispatch surface for handle-typed references: clicking, typing, or scanning an alter: URI yields a verified handle resolution rather than a free-text string or an unauthenticated fetch, and where an action is addressed it yields a verify-before-side-effect dispatch. This document requests provisional registration of the alter scheme with IANA per Section 3.

Introduction The ~handle identity primitive defined in binds a textual identifier (Sovereign, Bot, or Instrument tier per ) to a cryptographic principal published under an _alter. DNS TXT record. A handle reference written in running text, such as ~alice, ~example.com or ~cc-example-model, is interpretable to a human reader but is not, by itself, a dispatchable reference for a machine. This document defines the alter URI scheme as the dispatchable form of a handle reference. An alter: URI binds a ~handle to the resolution procedure of and to a URI handler registered with the host operating system. It carries three optional addressing components, an organisational scope, a facet, and an action-path. Once a handler is installed, clicking alter:~alice in a browser, chat window, or terminal yields a verified envelope; the handler decides what to do with the resulting envelope (open an inbox, show a profile card, initiate an Accord ceremony per , dispatch to a per-surface MCP tool). The scheme's addressing model is deliberately fuller than a bare handle. A reference frequently needs to name not just who but which organisational context, which facet of that identity, and which action surface under it. One example is "the security facet of ~blake at acme, verify action". The alter: scheme carries all four in a single dispatchable token, alter:~blake@acme:security/verify, so that the whole reference travels as one clickable, scannable, copy-pasteable string. Every component beyond the handle is OPTIONAL; a bare alter:~alice remains valid. This document specifies the addressing syntax, the dispatch and verification obligations of a handler, and the operating-system registration entries a handler installs. It does NOT specify the resolution semantics of any facet or action surface: what a given facet or action means, and how a resolver computes its answer, are owned by the specification that defines that surface and are out of scope here. This document is the standalone registration request submitted to IANA per Section 3, separating the administrative ceremony of scheme registration from the substantive specification of the DNS substrate.

Requirements Language The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 when, and only when, they appear in all capitals, as shown here.

Terminology

~handle

A textual identity reference defined in and tiered in . Handles begin with the tilde character U+007E.

Envelope

The signed identity record retrieved from the _alter.<domain> DNS TXT record of the publishing zone, as specified in Section 5.

Organisational scope

An optional DNS-named organisation qualifying a handle, written after an @ separator, e.g. ~blake@acme.example. The scope identifies the publishing zone under which the handle's envelope is resolved; a handle with no scope resolves under its own zone. org-scope selects the publishing zone consulted in the resolution procedure of Section 3.4; it carries no claim about which context, tenancy, or organisational capacity the presenting principal is presently acting under. A resolver, facet, or action-path definition MUST NOT infer the principal's acting context from the presence, absence, or value of org-scope. Where a reference needs to carry acting context, it does so via a context artefact reference (see Context Artefact Type below) or via a facet or action-path defined for that purpose by the surface that owns it, never via org-scope.

Facet

An optional named aspect of an identity, written after a : separator, e.g. :security. A facet narrows a reference to one addressable face of the identity. What a facet denotes, and how a resolver answers it, are defined by the surface specification that owns the facet, not by this document. An identity-pronoun reference axis is one example of the kind of specification that could own such a facet.

Action-path

An optional typed surface addressed under a handle (and facet, if present), expressed as the path component of the URI, e.g. verify, decisions/123, seat/architect. An action-path names an operation or resource surface; its semantics are owned by the specification that defines it.

Artefact type

A lowercase-alphabetic label identifying a member of a typed artefact genus, carried as the first path segment of an artefact-ref-form URI, e.g. nest in alter:nest/summary-42. An artefact type names a member of a genus whose extent is owned by the specification defining that genus, not by this document; this document defines the shape of the reference, not the genus it addresses.

Artefact reference

An opaque reference to one member of the genus named by an artefact type, carried as the second path segment of an artefact-ref-form URI, e.g. summary-42 in alter:nest/summary-42. What an artefact reference denotes, and how a resolver dereferences it, are defined by the surface specification that owns the artefact type, not by this document.

Handler

An operating-system component registered to receive alter: URIs and dispatch to a resolver. Examples include xdg-mime associations on Linux, LaunchServices URL handlers on macOS, registry entries under HKCR on Windows, intent filters on Android, and universal links on iOS.

Scheme Definition

Scheme Name alter

Status Provisional. This document requests provisional registration of the alter scheme per Section 3. A permanent registration per Section 7 is the intended upgrade path once the scheme specification stabilises; this document records that intent without asserting a permanent registration that IANA has not yet made.

URI Scheme Syntax The alter URI scheme's generic syntax conforms to . The scheme carries two disjoint reference forms under one scheme name:

The two alternatives of alter-URI are unambiguous because they are discriminated by the single octet immediately following the scheme separator alter:. U+007E TILDE (~) introduces a handle-ref-form reference; a lowercase ALPHA introduces an artefact-ref-form reference; no other leading octet is valid, and a URI beginning with any other octet MUST be rejected. The tilde character is reserved as the handle prefix under this scheme and MUST NOT begin an artefact-type; artefact-type is restricted to 1*LOWER for exactly this reason. A parser that inspects only this first octet can determine which grammar governs the remainder of the URI without backtracking. The handle-name ABNF mirrors the tier productions of without restating tier-level invariants; an alter: URI carries a single handle and the parser determines the tier from the lexical form. The four identity-bearing components of handle-ref-form are parsed left to right and each is bounded by its introducing delimiter: the handle follows the scheme separator, an @ introduces the organisational scope, the first : after the handle (or scope) introduces the facet, and the first / introduces the action-path. A : appearing after the first / is a literal action-segment character, not a facet delimiter, because the facet, if present, is fully consumed before any /. Every component after handle-ref is OPTIONAL and any combination MAY be omitted. The host-component slot of a generic URI is not used. All identity-bearing material is carried in the path-like productions immediately after the scheme separator; the @ in org-scope is a component delimiter within that material and MUST NOT be read as the userinfo @ of an authority. For the reference substrate of Section 3.6, this document is itself the specification that Terminology's Artefact type definition refers to: Section 3.9 enumerates the members currently admitted to the artefact-type genus under this document. That genus is a list of reference shapes maintained here; it is not, and does not govern, any closed set of storage or transport formats a consuming platform separately maintains for its own artefact-persistence purposes. A name MAY be a member of both without either list constraining the other's admission or carrying any resolution meaning across the two.

Scheme Semantics Operations on an alter: URI in handle-ref-form are retrieval-and-verify by default. Submitting an alter: URI in handle-ref-form to a handler MUST perform the resolution and verification procedure specified in Section 8 before any content, directive, or action derived from the resulting envelope is acted upon. Specifically, the handler MUST: Parse the URI per the ABNF above, isolating the handle, and any organisational scope, facet, and action-path. Resolve ~handle (under org-scope if present) to a publishing zone via the procedures of Section 6. Retrieve and DNSSEC-validate the _alter.<zone> TXT record. Verify the envelope signature against the published Ed25519 key per Section 8. If a facet or action-path is present, dispatch the request to the resolver indicated by the envelope, carrying the facet and action-path verbatim. Envelope retrieval in Step 3 is DNS-primary; where the _alter.<zone> TXT record is absent, falls back to the HTTPS Well-Known URI surface for envelope retrieval. This document imposes no requirement on that fallback beyond the verification procedure above, which applies uniformly regardless of which surface produced the envelope. The facet and action-path are ADDRESSING information only. This document assigns them no resolution meaning: it does not define what any facet denotes, how a resolver answers an action, or what value a dereference yields. Those semantics are owned entirely by the surface specification that defines the facet or action, and are out of scope here. A conforming handler treats the facet and action-path as opaque, verified-then-forwarded tokens. Where an action-path names an operation with a side effect, the verification of Step 4 is a precondition to that side effect: handlers MUST NOT perform, initiate, or authorise any action addressed by an alter: URI until the envelope has been retrieved and verified. Handlers SHOULD treat any verification failure as a hard error and SHOULD NOT fall back to unverified retrieval or to executing the addressed action. An alter: URI in artefact-ref-form addresses a typed artefact, not a ~handle. The resolution procedure of Steps 1-5 above is defined entirely in terms of DNS zone resolution for a handle and does not apply to it. This document assigns artefact resolution no meaning: it does not define how an artefact-type is resolved to a genus, how an artefact-ref is dereferenced to content, or what a handler does upon receiving one. Those semantics are owned entirely by the specification that defines the artefact genus named by artefact-type, exactly as facet and action-path semantics are owned by the surface specification that defines them. A conforming handler that receives an artefact-ref-form URI and has no such specification registered MUST treat it as unresolvable and MUST NOT attempt handle resolution against it.

Encoding Considerations alter URIs are ASCII per ; characters outside the unreserved set MUST be percent-encoded. The IRI form per is supported for action-paths that contain non-ASCII characters; the handle-ref, org-scope, and facet productions MUST be ASCII to align with the DNS label production of . The tilde character U+007E is reserved as the handle prefix and is treated as a literal, not as an unreserved-character escape.

Applications and Protocols That Use This Scheme A reference substrate operated by the present author uses alter: URIs to dispatch handle references between operating-system handlers, an alter command-line interface, chat clients, and agent runtimes that consume the DNS substrate of . Any agent runtime, client, or operating-system component that resolves ~handle references can register a handler for the scheme.

Interoperability Considerations Operating-system URI handler registries are well-defined for each target platform: Linux desktops: xdg-mime associations . macOS: CFBundleURLSchemes entries in an application's Info.plist . Windows: HKEY_CLASSES_ROOT\alter with URL Protocol and shell\open\command subkeys. Android: <intent-filter> with <data android:scheme="alter">. iOS: associated-domains and universal-link entitlement entries. Where multiple applications register a handler for alter:, the operating system's default-application policy applies. No special arbitration mechanism is defined by this document. Browsers MAY treat alter: URIs as opaque external schemes and delegate dispatch to the operating-system handler. Clients SHOULD NOT attempt direct retrieval of alter: URIs over HTTP; the resolution procedure of does not run over HTTP. The alter scheme does not displace any existing scheme and does not contradict the path-handling rules of . It coexists with https:, mailto:, and other schemes that an operating system may dispatch on the same surface.

Context Artefact Type context is a member of the artefact-type genus (Section 3.3), naming the reference shape for a context artefact. A context artefact is a first-class object the presenting principal holds, distinct from an organisational scope or a facet. This document specifies the reference shape only; it assigns no meaning to what a context artefact carries, in the same way it assigns no meaning to an artefact reference generally.

context-ref-form is artefact-ref-form with artefact-type = "context"; it introduces no third alternative to alter-URI and no change to the discriminator rule of Section 3.3. Worked forms: alter:context/personal, alter:context/9f2a-freelance-b. The RESERVED personal literal is the one exception to full opacity within this genus: because it is identical across every principal rather than an opaque per-context identifier, resolving it never distinguishes one principal's personal context from another's, and it reveals only that a personal-context resolution was attempted. A context artefact reference is a member-authored address naming which context artefact is meant. Determining which context is presently acting for a given session or request is outside the scope of this addressing specification, in the same way this document already declines to assign resolution meaning to a facet or an action-path; see Context Reference Confusion in Section 6.

Artefact Type Genus Membership Beyond context (Section 3.8), the reference substrate of Section 3.6 currently admits the following members to the artefact-type genus. Each names a reference shape only, in the same way Section 3.3 assigns artefact-ref no meaning beyond opacity within the named genus; none needs sub-grammar of its own, and each conforms to artefact-ref-form as specified.

docs

A static documentation artefact, e.g. alter:docs/protocol.md.

explainer

A plain-language explainer section, e.g. alter:explainer/07-where-your-name-earns.md.

guidance

A reciprocal-guidance document section, e.g. alter:guidance/00-what-you-owe.md.

nest

A design-nest document reference, e.g. alter:nest/summary-42. An artefact-ref in this genus member MAY carry a --<section> suffix naming a section within the referenced document, e.g. alter:nest/summary-42--3.1; the suffix is opaque within the artefact reference and needs no sub-grammar of its own.

agentframe

An inter-agent message frame, e.g. alter:agentframe/<frame-id>.

agentadvisory

An inter-agent advisory frame, e.g. alter:agentadvisory/<frame-id>.

consent

A member consent request, e.g. alter:consent/<approval-id>, optionally carrying an action query parameter naming a grant or decline disposition.

grant

A content-addressed grant envelope, e.g. alter:grant/sha256-<digest>.

stamp

A signed authorisation stamp, e.g. alter:stamp/<concern-domain>/<ref>. This member is the reason artefact-ref is a sequence of ref-segments rather than a single segment: the concern domain and the reference it scopes are separate names, and collapsing them into one segment would make the domain unreadable to anything but the emitter. A member of this genus MAY share its name with a format a consuming platform separately maintains for its own artefact storage, as grant, nest and stamp all do here; per Section 3.3, the coincidence carries no cross-governance between the two.

This list is not exhaustive of every reference the substrate of Section 3.6 may in future admit; a new member is admitted by describing its reference shape here, following this pattern or, where a member needs its own sub-grammar, the pattern of Section 3.8.

Security Considerations See Section 6 below.

Author / Change Controller Blake Morrison, Alter Meridian Pty Ltd, blake@truealter.com. Change control transfers to the IETF if this scheme is later specified by an IETF Stream document.

References , , , .

Operating-System Handler Registration The following non-normative subsections sketch the platform- specific registration entries that a conforming handler installs. Implementations are responsible for the platform-specific syntax; this document does not prescribe handler binaries or invocation shapes.

Linux desktops A .desktop file with MimeType=x-scheme-handler/alter; and a Exec= line invoking the platform resolver. The alter-cli reference implementation registers itself as the default handler on first run.

macOS A CFBundleURLTypes entry with CFBundleURLSchemes=("alter") and a CFBundleURLName of Identity Handle Reference in the application's Info.plist.

Windows Registry entries under HKEY_CLASSES_ROOT\alter: A default value of URL:Identity Handle Reference. A URL Protocol value of empty string. A shell\open\command subkey with the handler invocation.

Android An <intent-filter> declaring <data android:scheme="alter"/> on an Activity capable of performing the resolution procedure of Section 8.

iOS An associated-domains entitlement listing the publishing zone, plus a LSApplicationQueriesSchemes entry that includes alter.

Addressing Examples The following non-normative examples illustrate the addressing syntax. Facet and action semantics are out of scope; each surface is defined by the specification that owns it.

The first form addresses an envelope; the second and third address action surfaces under an envelope; the fourth scopes a handle to an organisation; the fifth adds a facet; the sixth adds a typed action under that facet; the seventh addresses a facet-scoped surface; the eighth illustrates Instrument-tier addressing.

Security Considerations

Verification Mandate The verification mandate of Section 8 is the security floor of this scheme. Handlers that accept an alter: URI without verifying the envelope's signature against the DNSSEC-validated publishing record violate the scheme's invariants. An attacker who induces a handler to perform unverified retrieval can substitute an envelope. Implementations MUST treat envelope verification as a precondition to any side effect (writing files, sending requests, dispatching a sub-handler, or performing an addressed action).

Action-Address Confusion Because an alter: URI MAY address a typed action, a handler that acts on the action-path before verifying the envelope exposes a confused-deputy surface: an attacker-supplied URI could name a privileged action under a handle the attacker does not control. The Step-4 verification MUST complete, binding the resolved envelope to the addressed handle, before any action-path is dispatched. A handler MUST NOT infer authority from the URI's textual form alone.

Context Reference Confusion A context artefact reference (Section 3.8) is a claim to verify, never authority to assume. A handler that treats the mere presence of a context artefact reference in an inbound request as sufficient to act under that context, without a separate admission step re-deriving the verdict against the principal's actual holdings, reproduces the confused-deputy surface described in Action-Address Confusion above, for the context axis rather than the action axis. A context artefact is a private holding, blind to every other context the same principal holds. The resolution procedure for a context artefact reference MUST NOT expose, to any party other than the presenting principal's own bound credential, the existence, name, or count of any other context the same principal holds. An unresolvable context-ref and a context-ref the resolver declines to answer MUST be indistinguishable; a resolver that distinguishes them creates an existence oracle over the principal's context set. No public resolution path is specified for context artefact references, and none should be built. Unlike a ~handle envelope, which is a published declaration under a zone its holder wants third parties to verify, a context artefact is resolvable only by its holder's own bound credential. A resolver receiving a context artefact reference from any other party MUST decline, in a way indistinguishable from the non-enumeration behaviour above.

Handler Substitution The operating-system's default-application policy is the trust-anchor for which binary handles alter: URIs. Users configuring the default handler MUST treat handler selection with the same caution they apply to default browsers or default mail clients. A malicious handler could parse an alter: URI, present a forged envelope to the user, and act on attacker-supplied data without performing verification. Implementations SHOULD cross-check the handler binary's signature against the publishing substrate's expected handler manifest where such a manifest is defined by a future specification.

Path-Component Privacy An organisational scope, facet, or action-path included in an alter: URI is part of the URI's textual form and may be logged by the operating-system handler registry, browser history, terminal scrollback, and chat-client indexers. Surface owners that consider a facet or action identifier (e.g. a decision identifier, a thread identifier) sensitive SHOULD provide indirected forms (opaque tokens, ephemeral identifiers) and SHOULD NOT recommend embedding sensitive identifiers in the URI.

Ref-Segment Traversal An artefact-ref is a sequence of named segments, not a filesystem path. A ref-segment MUST NOT be . or .., and MUST NOT be empty, so alter:explainer/../secret.md, alter:explainer//etc/passwd and alter:docs/ are all malformed and MUST be rejected. Implementations MUST reject them on the textual form, before any resolution is attempted, and MUST NOT normalise a navigation segment away and resolve what remains: a resolver that receives an already-normalised reference cannot tell that a traversal was ever requested. The percent-encoded spellings of these segments are covered by the same rule, because pct-encoded decoding happens before a segment is compared.

Cross-Scheme Confusion A URI of the form alter://~alice (with the authority-component double-slash) is malformed and MUST be rejected. Implementations MUST NOT silently coerce alter://~handle to alter:~handle; divergent parsers risk confusing a third-party authority component with a handle reference. Similarly, the @ of an org-scope MUST NOT be parsed as an userinfo delimiter; there is no authority component in an alter: URI.

Form Confusion The two forms defined in Section 3.3 share one scheme prefix and are discriminated solely by the octet following the scheme separator. A parser that accepts a leading tilde character inside an artefact-type production, or that treats an artefact-ref-form URI as containing a handle-ref when no tilde is present, breaks the partition between the two forms and creates a parser-divergence surface: two conforming implementations could disagree about which form a given URI carries, and an attacker could craft a URI that one implementation resolves as a handle reference and another resolves as an artefact reference. Implementations MUST reject any URI in which the octet following alter: is neither U+007E TILDE nor a lowercase ALPHA. Implementations MUST NOT attempt handle-ref-form parsing on a URI beginning with a lowercase ALPHA, and MUST NOT attempt artefact-ref-form parsing on a URI beginning with U+007E. A handler that dispatches based on a partial or best-effort match of either form, rather than a full match against the discriminator rule of Section 3.3, is non-conforming.

Handle-Domain Confusion handle-name admits U+002E FULL STOP, because the tier productions it mirrors from use a trailing .bot label to carry the bot tier lexically. A handle-name may therefore be spelled so that it resembles a DNS domain name. alter:~example.com is a well-formed handle reference naming a principal whose handle is example.com; it is not a reference to the example.com zone, and nothing in this scheme gives it one. Implementations MUST NOT derive DNS meaning from the lexical form of a handle-name, MUST NOT resolve a handle through DNS on the basis of its spelling, and MUST NOT treat a handle ending in a public suffix as evidence of any relationship to the corresponding domain. An association between a domain and a handle is established out of band and is never inferred from the handle's characters. A surface that renders a handle to a person MUST retain the leading tilde, because a handle stripped of its tilde and placed where a reader expects a domain cannot be distinguished from one. Only a trailing .bot label carries meaning under ; no other label within a handle-name carries any.

IRI Considerations When an alter: URI is presented in IRI form per with non-ASCII characters in the action-path, implementations MUST apply the conversion procedure of Section 3.1 before performing the resolution procedure. Non-ASCII characters in the handle-ref, org-scope, or facet MUST be rejected; those productions are restricted to the ASCII forms above.

IANA Considerations This document requests that IANA register the alter URI scheme in the Uniform Resource Identifier (URI) Schemes registry per Section 3 (provisional registration), recording the provisional registration cross-referenced under Section 11 with the following body: URI scheme name: alter Status: Provisional URI scheme syntax: As specified in Section 3.3 above. URI scheme semantics: As specified in Section 3.4 above. Encoding considerations: As specified in Section 3.5 above. Applications/protocols that use this URI scheme name: As specified in Section 3.6 above. Interoperability considerations: As specified in Section 3.7 above. Security considerations: As specified in Section 6 above. Contact: Blake Morrison blake@truealter.com, Alter Meridian Pty Ltd. Author/Change controller: Blake Morrison, Alter Meridian Pty Ltd. Change control transfers to the IETF if this scheme is later specified by an IETF Stream document. References: This document; ; . A permanent registration per Section 7 is the intended upgrade path once the scheme specification stabilises.

Acknowledgements The scheme builds on the ~handle identity primitive defined in and the tier taxonomy of . The lexical choice of tilde for the handle prefix is informed by and by the long-standing shell convention that the tilde denotes a named principal.

&RFC2119; &RFC8174; &RFC3986; &RFC7595; &RFC3987; &RFC4033; Alter Meridian Pty Ltd Alter Meridian Pty Ltd &RFC8615; Alter Meridian Pty Ltd Alter Meridian Pty Ltd

Change Log

draft-morrison-alter-uri-scheme-03 Add a Handle-Domain Confusion security consideration. handle-name admits "." in order to carry 's .bot tier suffix, so a handle may be spelled to resemble a DNS domain; state that no DNS meaning follows from a handle's lexical form, that a domain's association with a handle is established out of band, and that a rendering surface MUST retain the leading tilde. Make artefact-ref a sequence of ref-segments separated by "/" rather than a single segment, so a member whose reference carries a scoping name ahead of the reference itself is expressible; stamp, alter:stamp/<concern-domain>/<ref>, is the case that forced it. The slash is a separator between named segments and never a character within one, which is what keeps "//" and a trailing "/" malformed. Add a Ref-Segment Traversal security consideration. A ref-segment MUST NOT be "." or "..", MUST be rejected on the textual form before any resolution, and MUST NOT be normalised away and the remainder resolved; the rule is applied after pct-encoded decoding, so %2e%2e is refused on the same ground as ... Admit stamp to the artefact-type genus, and name nest and stamp alongside grant as the members whose names coincide with a consuming platform's own storage formats. Partition the scheme into two disjoint reference forms carried under one scheme name: handle-ref-form (unchanged from rev 02) and a new artefact-ref-form, alter:<artefact-type>/<artefact-ref>, addressing a typed artefact rather than a ~handle. Add a discriminator rule: the octet immediately following the scheme separator selects the form, U+007E TILDE for a handle reference and a lowercase ALPHA for an artefact reference; no other leading octet is valid, and the tilde is reserved as the handle prefix and MUST NOT begin an artefact type. Add Artefact type and Artefact reference to Terminology, defining the shape of the reference only; the extent of any artefact genus is owned by the specification defining that genus, not by this document. State that artefact resolution is assigned no meaning by this document, matching the existing disclaimer for facet and action-path semantics. Add a Form Confusion security consideration addressing the parser-divergence surface the two-form scheme introduces. Repoint the informative Apple reference from the archived Core Foundation keys page to the current CFBundleURLTypes page, and retitle it to match, because the archived URL cannot be rendered inside the 72-column limit at any reference indent. The mechanism cited is unchanged. Add context as a member of the artefact-type genus, with a Context Artefact Type subsection specifying context-ref-form, the RESERVED personal literal for the presenting principal's own organisation-free default context, and the opaque-reference production carrying a MUST-NOT-embed-a-handle-or-domain-label constraint. No top-level grammar change and no third alternative to alter-URI. Add a matching Context Reference Confusion security consideration covering the confused-deputy risk, non-enumeration of a principal's other contexts, and the absence of any public resolution path. Demote org-scope in Terminology from an implicit context carrier to a bare DNS zone qualifier, stating that a resolver, facet, or action-path definition MUST NOT infer acting context from it. Fix two grammar coverage gaps found by bringing an existing implementation into conformance against this scheme, rather than inventing new requirements. Widen artefact-ref from 1*( ALPHA / DIGIT / "." / "_" / "-" ) to 1*( unreserved / pct-encoded ), since ~ is unreserved per Section 2.3 and the character class as previously written could not carry a ~handle reference or its percent-encoded form; and make the artefact-ref component of artefact-ref-form OPTIONAL, since a bare artefact type with no ref had no production at all and several real "open this surface" addresses need exactly that shape. State, in URI Scheme Syntax, that this document is itself the specification owning the artefact-type genus for the reference substrate of Section 3.6, and that the genus is distinct from any closed set of storage or transport formats a consuming platform separately maintains; a name MAY be a member of both without either governing the other. Add an Artefact Type Genus Membership subsection listing the genus's current members beyond context (docs, explainer, guidance, nest, agentframe, agentadvisory, consent, grant), each a bare reference shape needing no sub-grammar of its own, and stating that membership is additive.

draft-morrison-alter-uri-scheme-02 Broaden the addressing syntax to the full ~handle@org:facet/action reference: add the org-scope, facet, and action-path productions and their left-to-right parsing rules. Every added component is OPTIONAL; a bare alter:~handle is unchanged. State explicitly that facet and action-path are addressing information only, with resolution semantics owned by the surface specification and out of scope here. Add an Action-Address Confusion security consideration and extend the verification mandate to cover addressed actions. Correct the registration Status to Provisional, matching the registration this document actually requests; record permanent registration as the intended upgrade path rather than asserting it.

draft-morrison-alter-uri-scheme-01 Editorial and reference alignment.

draft-morrison-alter-uri-scheme-00 Initial submission. Upgrades the provisional registration recorded in Section 11.