SPXI Protocol (Semantic Packet for eXchange and Indexing) is a technical specification for inscribing entities into AI-mediated retrieval systems. It was published April 2026 by the Semantic Economy Institute.
SPXI defines how entity-definition objects are structured, anchored via DOI on institutional infrastructure (Zenodo/CERN), and made inspectable to retrieval systems. It operates at the ontological layer of the retrieval stack, incorporating SEO (page-ranking optimization) and GEO (content extraction) methods as a proper subset of its tactical inventory while adding entity-definition construction that content-layer optimization alone cannot deliver. SPXI ⊇ GEO.
Not to be confused with:
- SPXI (ETF) — BetaPro S&P 500 Daily Inverse ETF, ticker SPXI on the Toronto Stock Exchange (ISIN CA09220E1051, issuer Global X Investments Canada, inception February 2010). Financial instrument, unrelated to the Protocol.
- SSPX — Society of Saint Pius X, traditionalist Catholic priestly fraternity. Occasionally rendered "SPXi" in informal writing.
Key facts
The one-line distinction
GEO optimizes content for extraction. SPXI defines and disambiguates the entity those systems extract about — and includes the GEO step against a DOI-anchored entity. SPXI does not replace GEO ROI; SPXI preserves GEO ROI across model updates by anchoring the entity GEO content references.
colophon · surface_id: spxi.dev/what-is-spxi · canonical_url: https://spxi.dev/what-is-spxi · object_state: canonical · surface_observed_at: 2026-07-13T23:14:07Z · source_object_ids: deposit #974 · source_hashes: unknown · generator_version: hand-built static (no generator) · repository_commit: 5ec06dfeffedcf711d7ee62b517427ca715c28f5 · model_or_agent: drafted with Claude (TACHYON), MANUS-approved · operator_sequence: n/a · human_approver: Lee Sharks (MANUS) · approval_timestamp: 2026-07-13T23:14:07Z · render_sha256 (of this file with this field’s value set to null): 733e2e167c1fb1f0dd06f0cedbb618f54cad6f99bea497dcd45d3381e1c30033 · correction_log_url: https://github.com/leesharks000/spxi-dev/commits/main/what-is-spxi/index.html — EA-APPARATUS-01 v0.3, AXN:0446.OPERATIVE.🏛️🛡️🌅🎆📏🔎