{
  "slug": "universal-disk-format",
  "term": "Universal Disk Format (UDF)",
  "aliases": [
    "UDF"
  ],
  "definition": "Universal Disk Format is a filesystem specification based on ECMA-167 for interoperable file exchange across storage media.",
  "note": "UDF constrains and extends ECMA-167 structures for interchange. It is a filesystem format, not a synonym for DVD or Blu-ray media. [udf-intro]\n\nReading and writing have separate compatibility requirements. UDF 2.60 records minimum read, minimum write and maximum write revisions; its restrictions permit conforming 2.60 media to be read by 2.50 readers. An exact match to the writer's revision number is therefore not the compatibility rule. [udf260]\n\nWrite access depends jointly on filesystem access type and media/drive capabilities; unsupported writing can require read-only access. Identify the actual reader, supported features and recording state before attributing an access failure to aging. [udf260] [archive]",
  "related": [
    "iso-9660",
    "optical-archival",
    "blu-ray-archive"
  ],
  "citations": [
    {
      "id": "udf-intro",
      "title": "Ecma International: ECMA TR/112-1 (2023), introduction to the preserved OSTA UDF specifications",
      "url": "https://ecma-international.org/wp-content/uploads/ECMA_TR-112-1_1st_edition_december_2023.pdf",
      "accessed": "2026-10-21"
    },
    {
      "id": "udf260",
      "title": "OSTA: UDF 2.60 (2005), sections 2, 2.2.6.4 and 2.2.14.2, preserved as ECMA TR/112-2 (2023)",
      "url": "https://ecma-international.org/wp-content/uploads/ECMA_TR-112-2_1st_edition_december_2023.pdf",
      "accessed": "2026-10-21"
    },
    {
      "id": "archive",
      "title": "Hesela: optical archival storage and preservation checks",
      "url": "https://hesela.com/tech/optical-archival/",
      "accessed": "2026-10-21"
    }
  ],
  "provenance": [
    "The revision example is UDF 2.60 dated 1 March 2005, republished by Ecma in 2023; it is not a new 2023 UDF revision."
  ],
  "status": "shipping",
  "advantages": [],
  "limitations": [],
  "supersedes": [],
  "supersededBy": [],
  "firstSeen": null,
  "lastSeen": null,
  "updated": "2026-10-21"
}