The spec for this action:
https://www.adobe.com/content/dam/acom/en/devnet/pdf/pdfs/PDF32000_2008.pdf#G11.2111850
An example of a form using this action:
https://www2.illinois.gov/rev/forms/reg/Documents/reg-1-mr.pdf
const obj = this._catDict.get("PageMode");
    let pageMode = "UseNone"; 
    if (isName(obj)) {
      switch (obj.name) {
        case "UseNone":
        case "UseOutlines":
        case "UseThumbs":
        case "FullScreen":
        case "UseOC":
        case "UseAttachments":
          pageMode = obj.name;
      }
    }
    return shadow(this, "pageMode", pageMode);
  }
  get viewerPreferences() {