What is the Universal Category System for sound effects, where is its official list published, which version and category list does it define, and under what terms?

UCS describes itself as a public-domain initiative offering a fixed category list and a filename structure for sound effects; its site (observed 2026-10-22) announces version 8.2.1 (January 2024). Its only distribution channel is a Dropbox shared folder reached through resources.universalcategorysystem.com, which a raw HTTP read cannot list, so no official specification text or official CSV was read at a stable URL. The 8.2.1 list can be read as plain CSV from three third-party repositories (each citing the UCS site as source): 753 CatID rows, 82 categories, columns Category, SubCategory, CatID, CatShort, Explanations, Synonyms. Terms are a self-description ('public domain'), not licence prose. Curator qualifications: UCS site: 'The Universal Category System (UCS) is a public domain initiative by Tim Nielsen, Justin Drury, Kai Paquin, among others'; 'All the resources for the UCS are available in our Dropbox repository'; 'Update (Jan, 2024): Version 8.2.1 ... to fix a typo and to extend the list of synonyms ... There are no new categories or subcategories in 8.2.1'. Third-party LICENSE begins: 'Creative Commons Attribution-ShareAlike 4.0 International (CC-BY-SA 4.0) https://creativecommons.org/licenses/by-sa/4.0'. Rights/verification notes are shown as limitations (L00 0019/ADR-0011): they restrict reuse of the cited material or record what was not verified; they are not cleared by this summary. Limitations: [rights_conflict_record] eligible_rights_conflict_preserved Evidence status: statements located in the cited sources by a correlated desk review (Claude); not executed; not independently reviewed.

{
  "citations": [
    {
      "url": "https://universalcategorysystem.com/",
      "note": "see curator disposition"
    },
    {
      "url": "https://resources.universalcategorysystem.com/",
      "note": "see curator disposition"
    },
    {
      "url": "https://github.com/jmrsound/ucs-tools/tree/2e307eb9aa4743a7a666426a9f70dcd08d393b40",
      "note": "see curator disposition"
    },
    {
      "url": "https://github.com/JunWooBeck/ucs-sfx-tools/tree/364f7204e56be8d11ba97e10334990525d475cb7",
      "note": "see curator disposition"
    },
    {
      "url": "https://github.com/brettbuddin/ucsrename/tree/9fa454378d50076edc67370ce56f60b3bbf9c43a",
      "note": "see curator disposition"
    },
    {
      "url": "https://www.dafx.de/paper-archive/2026/papers/DAFx26_paper_51.pdf",
      "note": "see curator disposition"
    }
  ]
}