{
  "schema_version": 1,
  "rules": {
    "identifiers": "NCES school IDs are strings. Preserve leading zeros; do not convert to numbers.",
    "percentages": "Percentages and percentiles use the 0–100 scale, not fractions. Achievement scores are standardized scores, not percentages or ACT composite scores.",
    "missing": "null means unavailable. Do not substitute zero or infer suppressed values. A missing bound is not an exact zero.",
    "rank": "Rank and percentile refer to eligible schools statewide, not the current city, category or comparison. Only eligible=true and a non-null rank establish a ranked school.",
    "partial_score": "Ineligible schools can retain a partial computed score. It is not a valid rank or proof of ranking eligibility; consult ineligibility_reason.",
    "periods": "Assessment summaries use the stated three-year window. NCES enrollment is a separate snapshot. Context metrics each have their own period. Do not divide tested counts by enrollment to estimate participation.",
    "admissions": "school_type and admissions_bucket are classifications. Only context.admissions records describe review status and date. Normal does not guarantee unrestricted enrollment or available places.",
    "sources": "context metric and annual-assessment source_id values join to sources[].id. ADE and NCES source attribution for the main ranking and directory is on source_ledger_url. Results do not imply official endorsement.",
    "citation": "Cite school.profile_url or area.canonical_url, include the assessment period or metric period, and link methodology_url when describing rank. Retain limitations and eligibility context.",
    "refresh": "Version 1 describes the file schema. Stable URLs serve the published build snapshot and may change with a validated release. Compare rankings_sha256 and context_sha256 to identify exact source snapshots; they are not hashes of individual files.",
    "reuse": "Project documentation and derived data are provided for inspection. Original sources retain their publishers' terms. No new blanket reuse license is asserted; see the site's terms and source ledger."
  },
  "fields": {
    "schema_version": "Integer contract version; currently 1.",
    "site_url": "Canonical site origin.",
    "data_year": "Last fiscal year of the assessment window; not a universal source or publication year.",
    "assessment_period": "Fiscal-year window for three-year assessment summaries.",
    "nces_enrollment_period": "Period of school.enrollment.",
    "snapshot_generated_at": "Generation time of the rankings snapshot, not a claim about the last edit of this page or the context data.",
    "rankings_sha256": "SHA256 of the exact source rankings.json bytes.",
    "context_sha256": "SHA256 of the exact source profile-context.json bytes.",
    "statewide_ranked_school_count": "Count of eligible ranked schools in the statewide snapshot.",
    "methodology_url": "Human-readable ranking contract.",
    "source_ledger_url": "Human-readable source provenance, verification and coverage.",
    "documentation_url": "Public endpoint and field documentation.",
    "dictionary_url": "Catalog link to the machine-readable field dictionary.",
    "school": "Single-school record in school files. Area files use schools[], with the same summary shape.",
    "school.nces_id": "String identifier, preserved exactly from the directory.",
    "school.name": "Published school name; names need not be unique statewide.",
    "school.profile_url / json_url / markdown_url": "Canonical citation page and corresponding single-school representations.",
    "school.district / district_id": "Published district name and identifier, each nullable.",
    "school.location": "address, city, county and zip are nullable strings; lat/lng are nullable coordinates in decimal degrees. Locations do not establish enrollment boundaries.",
    "school.school_type": "district, charter, magnet, online or alternative; some operators span multiple classifications.",
    "school.admissions_bucket": "normal, selective_admissions, online or alternative. This is independent of school_type.",
    "school.selective_admissions": "Published boolean context flag; not an Achievement input.",
    "school.website_url": "Nullable public school website URL from the directory.",
    "school.enrollment": "Nullable campus student count in the stated NCES period; may include lower grades.",
    "school.achievement": "score, percentile and rank are nullable numbers; eligible is boolean; ineligibility_reason is a nullable string; volatility_flag is a reserved boolean (disabled in v1). No scores are recomputed by this export.",
    "school.assessments": "act_ela, act_math and azsci: each object or null. Objects contain nullable students_tested_3yr, pct_passing_3yr, and pct_level_1_3yr through pct_level_4_3yr. Percentage summaries use the methodology's available-year aggregation and missing-count rules.",
    "context.annual_assessments": "Rows with fiscal year, subject (act_ela/act_math/azsci), nullable students_tested and pct_passing, and source_id. These are reported annual data, not reconstructed from three-year summaries.",
    "context.metrics": "Rows with metric, nullable value, unit (percent/students/grade), period, status, source_id, nullable accountability_model and optional reported_bound. Current metrics include graduation_4yr, graduation_5yr, dropout and enrollment; af_grade and open_enrollment are reserved and remain unpublished until verified.",
    "context.metrics.status": "final, provisional, revised, not_rated, suppressed or missing. Preserve it alongside the value.",
    "context.metrics.reported_bound": "<2 or >98, or null/absent. A bound accompanies a null exact value; never replace it with a midpoint or endpoint.",
    "context.admissions": "status (reviewed/source_on_file/unreviewed), nullable reviewed_on and source_url, and an evidence note. A reviewed date is not a promise that the policy is still unchanged.",
    "sources": "Applicable source references: id, title, url, retrieved_on, sha256, verified, sample_school_ids and verification_note.",
    "area": "kind (cities/counties/districts), slug, name and canonical_url. The grouping_note explains geographical limits.",
    "schools": "Area summary rows or catalog entries. Catalog entries contain nces_id, name, profile_url, json_url and markdown_url only.",
    "areas": "Catalog entries with kind, slug, name, canonical_url and json_url."
  }
}