Every petition for redetermination shall be in writing and shall state the specific grounds upon which the petition is founded. The petition may be amended to state additional grounds at any time prior to the date on which the board issues its order or decision upon the petition for the redetermination.
Source:
Section 7710.5, https://leginfo.legislature.ca.gov/faces/codes_displaySection.xhtml?lawCode=RTC§ionNum=7710.5..