Functional Extraction and Structural Continuity: The Selective Survival of Indus Administrative Frame Signs into the South Indian Megalithic Period (1900–600 BCE)

This deposit establishes intellectual priority over the following finding: the transition from the Indus Valley script to the South Indian Megalithic graffiti corpus (1900–600 BCE) was not random cultural drift but a Functional Extraction — the selective survival of the administrative frame layer (openers and closers) while the administrative content layer (medial signs) was completely discarded. Three independent statistical tests confirm this finding. Fisher's exact test on the sign survival contingency table yields p = 1.62 × 10⁻¹⁹, odds ratio 16.7 — high-lock signs (openers and closers) are 16.7 times more likely to survive into the megalithic graffiti corpus than low-lock signs. Spearman rank correlation between positional lock strength in the 3rd millennium BCE and graffiti survival frequency in the 1st millennium BCE yields ρ = 0.542 (n = 60), independently confirming the Fisher result. The medial sign control group — 12 purely medial signs with 0.0% frequency in both initial and final positions across the full Mahadevan corpus — achieves 0% survival. Zero out of twelve. No statistical test required. The 1,300-year period between the Indus urban collapse (~1900 BCE) and the Tamil-Brahmi emergence (~600 BCE) is identified as a structural TRANSITIONAL band, not an evidential gap. The Meluhhan Interregnum Hypothesis is named and defined: the administrative frame persisted in degraded low-fidelity form — pottery graffiti rather than institutional seals — carrying the structural skeleton forward until the Tamil-Brahmi phonologization event at Keezhadi and Adichanallur mapped the identity-marking tokens onto spoken Dravidian. This deposit does not claim phonetic continuity between the Indus script and Brahmi. The claim is structural and precise: the signs that survived into the proto-Brahmi period are specifically the signs that carried identity-marking function in the Indus administrative grammar, and this selectivity is measurable and non-random at p < 10⁻¹⁹. Findings are tagged to three interpretation layers: Layer S (observable sign survival counts), Layer F (statistical selectivity — the primary deposit claim), and Layer G (functional extraction mechanism and civilizational interpretation). This deposit extends Molina (2026a–d) — the structural falsification of Sproat (2004), the functional decipherment of the Indus script across 2,543 inscriptions, the 100% administrative grammar confirmation across all 9 artifact materials, and the full structural closure of the corpus. Positional lock classifications used in this analysis are established in those prior deposits. Full analytical methodology withheld pending peer-reviewed publication. SHA-256 of companion private deposit embedded in document. Data sources: Lal (1960) Ancient India No. 16, Mahadevan (2006/2014) Dravidian Proof studies, Yadav et al. (2008) Current Science 95(11), CISI (Parpola et al.), yajnadevam/indus-website (GPL-3.0). All statistical results independently reproducible from public corpora.