{
  "node_id": "issn-serial-standard",
  "title": "ISSN (Serial Standard)",
  "domain": "Creative, Content & Media IP",
  "version": "1.1.0",
  "last_updated": "2026-04-10",
  "bluf": "International Standard Serial Number (ISSN) compliance mandates stringent data integrity and structural validation for all applicable serial publications. A designated 'issn' field must be present and conform to the canonical 'NNNN-NNNC' format, where the final character is a digit or an uppercase 'X'. The unhyphenated string must possess a length of exactly 8 characters, comprising seven initial digits and a final valid check character. Correctness is further enforced through a 'Modulo 11' checksum calculation, which algorithmically validates the eighth digit based upon the preceding seven. An ISSN is required for asset types classified as 'serial', 'journal', 'magazine', 'newsletter', or 'periodical'. Procedurally, the existence of an ISSN implies the mandatory presence of a corresponding, non-null publication title. Uniqueness is paramount; the system prohibits duplicate ISSN assignment across distinct publication titles. For external verification, each ISSN must be confirmed as officially registered and active through an API lookup against the ISSN International Centre's portal. Finally, if a single publication title has more than one format-specific identifier, the designation of a linking ISSN-L becomes a requirement to ensure cohesive resource identification. This comprehensive rule set ensures all managed serials adhere to global cataloging and identification standards.",
  "paywall": {
    "status": "LOCKED",
    "unlock_cost_usd": "0.01",
    "skyfire_id": "41779894-ece2-4163-9761-b3b1b76e19b0"
  },
  "crosswalks": {
    "_available_keys": [
      "nist_framework",
      "iso_standard",
      "ai_overlay_2026",
      "industry_mapping"
    ],
    "_note": "Full crosswalk values included in vault response"
  },
  "dependencies": [
    "isbn-book-standard",
    "doi-digital-object-id"
  ],
  "primary_citations_count": 6
}