Notwithstanding Section 15620 of the Government Code, the board, by order entered upon its minutes and for good cause shown, may extend the time fixed for filing portions of the property statement as follows:
(a)
For any part of the property statement relating to the development of the unit value of operating property, an extension not exceeding 45 days may be granted.
(b)
For any part of the property statement, not relating to the development of the unit value of operating property, that lists or describes specific operating property, an extension not exceeding 30 days may be granted.
(c)
For any part of the property statement that lists or describes specific nonunitary property, an extension not exceeding 30 days may be granted.
(d)
If an extension is granted pursuant to subdivision (a), (b), or (c), an additional 15-day extension may be granted upon the showing of extraordinary circumstances which prevent the filing of the statement within the first extension.