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
if (typeof cTrigger !== "string" || typeof cScript !== "string") {
      return;
    }
    if (!(cTrigger in this._actions)) {
      this._actions[cTrigger] = [];
    }
    this._actions[cTrigger].push(cScript);
  }
  setFocus() {
    this._send({ id: this._id, focus: true });
  }
  setItems(oArray) {
    if (!this._isChoice) {
      throw new Error("Not a choice widget");
    }
    this._items.length = 0;
    for (const element of oArray) {
      let displayValue, exportValue;
      if (Array.isArray(element)) {
        displayValue = element[0]?.toString() || "";
        exportValue = element[1]?.toString() || "";
      } else {
        displayValue = exportValue = element?.toString() || "";
      }
      this._items.push({ displayValue, exportValue });
    }
    this._currentValueIndices = 0;
    this._send({ id: this._id, items: this._items });
  }
  setLock() {}