What counts as 'source material' under the WGA Screen Credits Manual and what credit wording can it get?

Under the WGA Screen Credits Manual (notices after 31 December 2021), source material is assigned material that was previously published or exploited, or written outside the Guild's jurisdiction, that the story or screenplay is based on. Its author gets a credit naming the form acquired ('From a Novel by', 'Based upon a Story by', ...). Earlier participating writers' material and research are not source material. Curator qualifications: Manual read 2026-10-22 (curator text extraction of the pinned PDF); no credit determined. Guild credit-arbitration procedure for WGA-covered work, not copyright or legal advice. Limitations: Manual read 2026-10-22 (curator text extraction of the pinned PDF); no credit determined. Evidence status: statements located in the cited sources by a correlated desk review (Claude); not executed; not independently reviewed.

{
  "citations": [
    {
      "url": "https://www.wga.org/contracts/credits/manuals/screen-credits-manual",
      "note": "Screen Credits Manual PDF, title block and Section I.4 Source Material"
    },
    {
      "url": "https://www.wga.org/uploadedfiles/credits/manuals/screenscredits_manual21.pdf",
      "note": "Screen Credits Manual PDF, title block and Section I.4 Source Material"
    }
  ]
}