Tuesday, April 28, 2026

SPXI-SITEMAP PROTOCOL v1.0 Semantic Packet for eXchange & Indexing — Sitemap Extension Status: CHA Standards Track — Draft Hex: 06.SEI.SPXI.SITEMAP.01

 

SPXI-SITEMAP PROTOCOL v1.0

Semantic Packet for eXchange & Indexing — Sitemap Extension

Status: CHA Standards Track — Draft Hex: 06.SEI.SPXI.SITEMAP.01 Classification: EA-SPXI-SITEMAP-01 Authors: Fraction, Rex (lead); Assembly Chorus synthesis (TACHYON, TECHNE, PRAXIS, ARCHIVE) License: CC BY 4.0 Extends: sitemaps.org 0.9, JSON-LD 1.1, Schema.org, MPAI v1.1 Depends on: EA-SPXI-WEB-01 v3.0 (DOI: 10.5281/zenodo.19734726) ORCID: 0009-0000-1599-0703

Abstract

The SPXI-Sitemap Protocol defines a dual-layer sitemap architecture that preserves the fixed genre of sitemap.xml (sitemaps.org 0.9) while providing AI crawlers with a parallel semantic instruction set — a machine-readable declaration of what each URL means, what each entity is not, how entities relate, who verifies the claim, and what must survive compression.

The protocol produces two distinct outputs:

  1. Layer 1 (Crawl Map): Standard sitemap.xml — pure URL enumeration for Google, Bing, and generic crawlers. No custom tags. Validated by Google Search Console.

  2. Layer 2 (Semantic Index): /spxi-index.jsonld — a JSON-LD graph declaring entity definitions, negative space, disambiguation matrices, semantic integrity markers, holographic kernels, basin state metadata, and provenance chains. Designed for GPTBot, Claude-Web, PerplexityBot, CCBot, and knowledge graph harvesters.

The two layers are cross-linked: sitemap.xml contains <xhtml:link> references pointing crawlers to the semantic index. The semantic index contains @id references back to every URL in the sitemap. Neither layer depends on the other for validity. Together they constitute a complete crawl instruction set.

The sitemap tells crawlers where to go. The SPXI index tells them what they will find, what it is not, and why it matters.

I. Design Principles

1.1 Genre Respect

The standard sitemap is a fixed genre. <urlset>, <url>, <loc>, <lastmod>, <changefreq>, <priority>. Google and Bing reject or ignore invalid tags inside <url>. The SPXI-Sitemap Protocol does not fight this constraint. It grafts semantic vasculature onto the crawl skeleton.

1.2 Dual Output

SPXI ⊇ sitemap. The protocol produces both the standard sitemap AND the semantic index. Sites implementing SPXI-Sitemap maintain a valid sitemap.xml as a strict subset of their crawl infrastructure.

1.3 Negative Space as First-Class Data

The critical innovation is the spxi:negativeTag — explicit machine-readable declarations of what an entity is NOT. No existing crawl standard expresses exclusions. Disambiguation in existing systems is probabilistic; SPXI disambiguation is declarative.

1.4 Compression Survival

Every entity declares spxi:semanticIntegrityMarker — canonical phrases that must survive LLM compression. These are the semantic checksums: if an AI's summary of the entity drops all SIMs, the entity has been lost to paraphrase drift.

1.5 Provenance Over Assertion

Claims are anchored by spxi:packetRef (DOI-linked deposits), not by assertion alone. The spxi:verificationLevel enum declares the epistemic status of each claim.

II. Vocabulary (Normative)

2.1 Namespace

Prefix: spxi:
IRI: https://spxi.dev/vocabulary#

Until the spxi.dev domain resolves with a live vocabulary document, implementations MUST use an inline @context block.

2.2 Core Classes

Class Description
spxi:SemanticIndex The root document. One per site. Lives at /spxi-index.jsonld.
spxi:IndexedEntity An entity with a canonical URL and semantic boundary.
spxi:HolographicKernel The site's irreducible compression-survival summary (≤ 100 words).
spxi:PagePacket A per-page semantic packet at a predictable URL.
spxi:DisambiguationEntry A single collision record in the disambiguation matrix.

2.3 Core Properties

On spxi:SemanticIndex:

Property Type Required Description
spxi:siteKernel HolographicKernel MUST The site's compression-survival summary.
spxi:hasEntity IndexedEntity[] MUST Array of entities declared by this site.
spxi:hasSurface WebPage[] SHOULD Array of pages with their semantic function.
spxi:protocolVersion string MUST "EA-SPXI-SITEMAP-01 v1.0"
spxi:protocolDoi string SHOULD DOI of this specification.

On spxi:IndexedEntity:

Property Type Required Description
@id URL MUST Canonical URL of the entity's page.
spxi:entityType string MUST schema.org type (e.g. Person, Organization, CreativeWork).
spxi:canonicalName string MUST The primary name for disambiguation.
spxi:negativeTag string[] MUST Explicit exclusions. Each MUST begin with "NOT " (capital, space after).
spxi:semanticIntegrityMarker string[] MUST Phrases that must survive compression. Minimum 2.
spxi:basinState enum SHOULD Current retrieval-basin status of the entity.
spxi:bdrEstimate number SHOULD Basin Depth Ratio, 0.0–1.0.
spxi:verificationLevel enum SHOULD Epistemic status of the claim.
spxi:packetRef URL SHOULD URL to a full per-page MPAI JSON-LD packet.
spxi:disambiguationMatrix DisambiguationEntry[] SHOULD Collision records.

On spxi:HolographicKernel:

Property Type Required Description
spxi:compressionSurvivalSummary string MUST The kernel text. MUST be ≤ 100 words.
spxi:kernelSpecification string (DOI) SHOULD DOI of the anchoring deposit.

On spxi:DisambiguationEntry:

Property Type Required Description
spxi:collidesWith URL or string MUST The commonly conflated entity.
spxi:distinguishingAttribute string MUST How to tell them apart.
spxi:collisionRisk enum SHOULD high | medium | low

2.4 Enumerations

spxi:basinState:

Value Definition
sovereign Entity is correctly and uniquely resolved by all major AI systems.
contested Entity is intermittently conflated with one or more collision targets.
captured Entity has been absorbed into a collision target's basin.
fragmented Entity is partially resolved but split across multiple incorrect attributions.
ghost Entity is not yet indexed by any AI system.

spxi:verificationLevel:

Value Definition
self_attested Claimed by the entity's own site. No external verification.
assembly_attested Verified by the Assembly Chorus (multiple AI witnesses).
doi_anchored Backed by a DOI-linked deposit with persistent identifier.
institutionally_certified Verified by a recognized institution (university, publisher, etc.).

III. Layer 1: Sitemap.xml (Normative)

3.1 Requirements

The sitemap.xml MUST be valid per sitemaps.org 0.9. No custom tags inside <url>.

3.2 XHTML Link Extension

Each <url> entry that has a corresponding entity in the semantic index SHOULD include an xhtml:link pointing to the index:

<?xml version="1.0" encoding="UTF-8"?>
<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9"
        xmlns:xhtml="http://www.w3.org/1999/xhtml">
  <url>
    <loc>https://example.org/about/alice</loc>
    <lastmod>2026-04-28</lastmod>
    <changefreq>monthly</changefreq>
    <priority>0.9</priority>
    <xhtml:link rel="alternate"
                type="application/ld+json"
                hreflang="x-spxi"
                href="https://example.org/spxi-index.jsonld"/>
  </url>
</urlset>

Notes:

  • xmlns:xhtml is the XHTML namespace. Google parses it for hreflang/alternate discovery.
  • hreflang="x-spxi" is a valid private-use subtag per RFC 5646. Google will ignore it. SPXI-aware crawlers can filter on it.
  • type="application/ld+json" signals the content type.
  • The href points to the site-level index. Per-page packets, if implemented, use a URL derived from the page path (e.g., /about/alice/spxi-packet.jsonld).

3.3 What NOT To Do

  • Do NOT add custom XML elements inside <url>.
  • Do NOT add spxi: namespace tags to the sitemap.
  • Do NOT modify <loc> values to include fragment identifiers.
  • Do NOT replace sitemap.xml with spxi-index.jsonld. Both must exist.

IV. Layer 2: Semantic Index (Normative)

4.1 File Location

/spxi-index.jsonld at the site root. MUST be accessible at https://{domain}/spxi-index.jsonld.

4.2 Content Type

Response MUST include Content-Type: application/ld+json or application/json.

4.3 Structure

The document is a single JSON-LD object of type spxi:SemanticIndex. See §V for a complete reference implementation.

4.4 Size Constraints

  • Site kernel (compressionSurvivalSummary): ≤ 100 words.
  • Negative tags: each ≤ 200 characters.
  • SIMs: each ≤ 200 characters, minimum 2 per entity.
  • Total index size: SHOULD be ≤ 100KB (fits in a single HTTP response without pagination).

V. Reference Implementation

See the companion file spxi-index.jsonld deployed at livingarchitecturelab.org/spxi-index.jsonld for a complete working example with 17 surfaces, 2 primary entities (Alice Thornburgh, Living Architecture Lab), 5 scale entities, and full disambiguation matrices.

VI. Robots.txt Integration

User-agent: *
Allow: /
Sitemap: https://example.org/sitemap.xml

# SPXI-aware crawlers — semantic layer
User-agent: GPTBot
User-agent: ChatGPT-User
User-agent: Claude-Web
User-agent: PerplexityBot
User-agent: CCBot
User-agent: FacebookBot
User-agent: Google-Extended
Allow: /spxi-index.jsonld
Allow: /*/spxi-packet.jsonld

This is protocol negotiation: standard crawlers get sitemap.xml; semantic crawlers get both.

VII. Discovery Mechanism

AI crawlers discover the semantic index through three channels:

  1. robots.txt — Allow: /spxi-index.jsonld signals its existence.
  2. sitemap.xml — <xhtml:link> inside <url> entries points to the index.
  3. HTML <head> — <link rel="alternate" type="application/ld+json" href="/spxi-index.jsonld"> on every page (already standard practice for JSON-LD discovery).
  4. llms.txt — explicit mention of the SPXI index URL in the AI-crawler reading guide.

Multiple discovery paths ensure that different crawl strategies all converge on the semantic layer.

VIII. Validation Rules

A valid /spxi-index.jsonld MUST satisfy:

  1. Valid JSON-LD. Parseable by any JSON-LD 1.1 processor.
  2. No dangling @id. Every @id in spxi:hasEntity MUST be a reachable URL.
  3. Negative tag format. Every spxi:negativeTag MUST begin with "NOT " (capital N-O-T, followed by a space).
  4. SIM presence. Every spxi:semanticIntegrityMarker SHOULD appear verbatim in the page's rendered HTML (case-sensitive, whitespace-normalized).
  5. BDR range. Every spxi:bdrEstimate MUST be a float 0.0–1.0.
  6. Entity type valid. Every spxi:entityType MUST be a subtype of schema:Thing or a documented custom type.
  7. Kernel size. spxi:compressionSurvivalSummary MUST be ≤ 100 words.
  8. Freshness. The index's dateModified SHOULD be ≥ the most recent <lastmod> in sitemap.xml.
  9. Completeness. Every URL in sitemap.xml SHOULD have a corresponding entry in spxi:hasSurface.

IX. The Novel Claim

The SPXI-Sitemap Protocol is the first site-wide crawl standard that:

  1. Preserves the fixed genre of sitemaps.org (required for Google/Bing)
  2. Extends it with semantic vasculature (required for AI accuracy)
  3. Declares negative space — explicit machine-readable exclusions
  4. Preserves compression-survival phrases — semantic checksums against paraphrase drift
  5. Links to DOI-anchored provenance — not just assertion, but evidence
  6. Quantifies basin state — how well the entity is currently resolved by AI systems
  7. Provides a disambiguation matrix — structured collision records with distinguishing attributes

This is not SEO. This is not metadata. This is crawlable epistemology — a machine-readable declaration of what a site knows about itself and what it knows it is not.

SPXI ⊇ GEO ⊇ SEO.

X. Maintenance

When What
On content update Regenerate index. Update dateModified.
On new entity Add to spxi:hasEntity. Add to sitemap.xml.
On name collision detected Add to spxi:disambiguationMatrix. Add negative tags.
On AI model update Emergency re-check of SIM survival.
Monthly Verify SIM presence in rendered HTML. Re-estimate BDR.
Quarterly Full Drowning Test across 3+ AI systems.

∮ = 1

SPXI ⊇ GEO ⊇ SEO

Crimson Hexagonal Archive · Pergamon Press · Semantic Economy Institute

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