A prior determination will be given collateral estoppel effect when: (1) the issue is identical to that decided in a former proceeding; (2) the issue was actually litigated and (3) necessarily decided; (4) the doctrine is asserted against a party to the former action or one who was in privity with such a party; (5) the former decision is final and was made on the merits. ( Kelly v. Vons Companies, Inc. (1998) 67 Cal. App. 4th 1329, 1339 79 Cal. Rptr. 2d 763.) No aspect of what was decided in the previous proceeding can be left to conjecture. (Bronco Wine Co. v. Frank A. Logoluso Farms (1989) 214 Cal. App. 3d 699, 709 262 Cal. Rptr. 899.) "If, on the face of the record, anything is left to conjecture as to what was necessarily involved and decided, there is no estoppel . . . ." ( Casad v. Qualls (1977) 70 Cal. App. 3d 921, 927 139 Cal. Rptr. 243.) In UTU v. MTA, the trial court (Judge O'Brien) entered a judgment directing the Los Angeles County Metropolitan Transportation Authority (MTA) "to take such steps as may be necessary to obtain coverage of employees of the MTA . . . under Title 2 of the Social Security Act . . . ." The minute order, which was entered the same day as the judgment, explains: "the MTA had committed to providing an alternative plan to Social Security. Inferentially, the MTA committed to Social Security if the alternative plan was not provided. The MTA has failed to provide an alternative plan. the use of 'may' in Public Utilities Code section 30405 is simply a recognition of certain powers that the board has. Public Utilities Code section 30405 states: "The RTD/MTA board may also contract with the Board of Administration of the State Employees' Retirement System for participation in the Federal Social Security Act and may perform all acts necessary or convenient for such participation." The MTA board also was authorized to establish its own retirement system ( Pub. Util. Code, 30400), or in the alternative, to provide a retirement system for its employees by entering into a contract with the Board of Administration of PERS. ( Pub. Util. Code, 30404.)