Cal. Pub. Resources Code § 25516.5
On a notice which proposes an expanded ultimate electric generating capacity for a site, the commission may, based upon findings pursuant to Section 25514, either approve the notice only for the initial facility or facilities proposed for operation within the forthcoming 12-year period or may approve the notice for the initial facility or facilities and find the site acceptable for additional generating capacity of the type tentatively proposed. The maximum allowable amount and type of such additional capacity shall be determined by the commission.
If a notice is approved which includes a finding that a particular site is suitable to accommodate a particular additional generating capacity, the site shall be designated a potential multiple-facility site. The commission may, in determining the acceptability of a potential multiple-facility site, specify conditions or criteria necessary to insure that future additional facilities will not exceed the limitations of the site.
Ca. Pub. Res. Code § 25516.5