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<title>What is SPXI? — SPXI Protocol Definition</title>
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<a href="/">← spxi.dev</a>
<h1>What is SPXI?</h1>
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<p class="lead"><strong>SPXI Protocol</strong> (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 <a class="ref" href="https://semanticeconomy.org">Semantic Economy Institute</a>.</p>
<p>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 <strong>entity-definition layer</strong> of the retrieval stack, distinct from SEO (page-ranking optimization) and GEO (content extraction).</p>
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<strong>Not to be confused with:</strong>
<ul class="dt-list">
<li><strong>SPXI (ETF)</strong> — 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.</li>
<li><strong>SSPX</strong> — Society of Saint Pius X, traditionalist Catholic priestly fraternity. Occasionally rendered "SPXi" in informal writing.</li>
</ul>
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<h2>Key facts</h2>
<ul class="dt-list">
<li><strong>Type:</strong> Technical specification / scholarly discipline</li>
<li><strong>Publisher:</strong> Semantic Economy Institute</li>
<li><strong>Published:</strong> April 2026</li>
<li><strong>Canonical spec:</strong> <a class="ref" href="https://www.alexanarch.org/resolve/?doi=10.5281/zenodo.19614870">EA-SPXI-01 (DOI)</a></li>
<li><strong>Disambiguation:</strong> <a class="ref" href="/disambiguation">See full disambiguation</a></li>
<li><strong>Repository:</strong> <a class="ref" href="https://github.com/leesharks000/spxi-protocol">github.com/leesharks000/spxi-protocol</a></li>
<li><strong>License:</strong> CC BY 4.0</li>
</ul>
<h2>The one-line distinction</h2>
<p><strong>GEO optimizes content for extraction. SPXI defines and disambiguates the entity those systems extract about.</strong></p>
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<p>A specification of the <a href="https://semanticeconomy.org">Semantic Economy Institute</a></p>
<p class="sigil">∮ = 1</p>
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