California Code, Government Code - GOV § 66498.2

If the ordinances, policies, or standards described in subdivision (b) of Section 66498.1 are changed subsequent to the approval or conditional approval of a vesting tentative map, the subdivider, or his or her assignee, at any time prior to the expiration of the vesting tentative map pursuant to subdivisions(b), (c), and (d) of Section 66498.5, may apply for an amendment to the vesting tentative map to secure a vested right to proceed with the changed ordinances, policies, or standards.  An application shall clearly specify the changed ordinances, policies, or standards for which the amendment is sought.