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
return this._value;
  }
  set value(value) {
    if (value === null || value === undefined) {
      this._value = "";
    }
    const i = this.exportValues.indexOf(value);
    if (0 <= i && i < this._radioIds.length) {
      this._id = this._radioIds[i];
      this._value = value;
    } else if (value === "Off" && this._radioIds.length === 2) {
      const nextI = (1 + this._radioIds.indexOf(this._id)) % 2;
      this._id = this._radioIds[nextI];
      this._value = this.exportValues[nextI];
    }
  }
  checkThisBox(nWidget, bCheckIt = true) {
    if (nWidget < 0 || nWidget >= this._radioIds.length || !bCheckIt) {
      return;
    }
    this._id = this._radioIds[nWidget];
    this._value = this.exportValues[nWidget];
    this._send({ id: this._id, value: this._value });
  }
  isBoxChecked(nWidget) {