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.textColor;
  }
  set fgColor(color) {
    this.textColor = color;
  }
  get value() {
    return this._value;
  }
  set value(value) {
    if (value === "") {
      this._value = "";
    } else if (typeof value === "string") {
      switch (this._fieldType) {
        case FieldType.number:
        case FieldType.percent:
          value = parseFloat(value);
          if (!isNaN(value)) {
            this._value = value;
          }
          break;
        default:
          this._value = value;
      }
    } else {
      this._value = value;
    }
    if (this._isChoice) {
      if (this.multipleSelection) {
        const values = new Set(value);
        this._currentValueIndices.length = 0;