Here's how BART and its two unions describe the events that unfolded in the dispute over a family leave provision the agency says was mistakenly included in the partially approved labor contracts:

May 13 -- Bargaining starts among BART and the Amalgamated Transit Union Local 1555 and Service Employees International Union Local 1021.

May 30 -- Family leave provision discussed in negotiation session.

June 5 -- Union offers to withdraw the family leave provision in exchange for approval of a larger package.

June 6 -- BART says it rejected the union's family leave provision and the larger package. Union says the family leave provision was not withdrawn.

June 24 -- BART says its chief negotiator, Thomas Hock, confirmed that the family leave provision was withdrawn. Unions dispute Hock's recollection. The unions file a lawsuit in Alameda Superior Court, alleging that BART was bargaining in bad faith and engaged in unfair labor practices.

July 1-4 -- BART employees strike.

July 11-19 -- BART says a temporary employee erroneously typed up the family leave provision under Hock's direction as an official tentative agreement -- one of many that make up the contracts as a whole -- and he signed it.

August 7 -- BART and unions present their cases to the Governor's Board of Inquiry after the agency requested a 60-day cooling off period. BART says the family leave provision was not included. The unions say it was part of the package.

Aug. 10 -- BART makes counteroffer and says the family leave provision was not in the package. Unions say they "never relied" on the attachments as they "did not accurately reflect the status" of the talks.

Aug. 11-Oct. 12 -- 60-day cooling off period.

Oct. 13 -- BART makes a "last, best and final" offer and says the list of tentative agreements does not include the family leave provision. Unions say that may be true but, if so, the agency didn't inform them of their decision to withdraw the section.

Oct. 18-20 -- BART employees strike.

Oct. 21 -- BART and unions reach a deal. ATU sends email to its workers promoting 20 aspects of the deal but not what would be a new family leave provision.

Oct. 22-28 -- BART and unions hold tentative agreement checkoff sessions and exchange correspondence.

Oct. 31 -- BART provides the unions with a final set of tentative agreements, which includes the family leave provision section 4.8. It was signed by five union negotiators and three agency representatives, probably back in July. BART says its inclusion was an error. Unions say it was not.

Nov. 1 -- Union members ratify the contracts, including the disputed family leave provision.

Nov. 4 -- BART staff reviews the tentative agreement documents, discovers the family leave provision had been included and informs the unions of the error.

Nov. 7 -- BART attorney Vicki Nuetzel advises two union lawyers that the district cannot ratify the contract. "Those who were present during bargaining cannot in good faith contend that the district agreed to this proposal, and it is troubling that you have chosen to take the positions that you have," Nuetzel wrote.

Nov. 14 -- BART board votes 7-1 to send staff back into negotiations, but the unions refuse. The agency estimates the family leave provision could cost the agency over the four-year contract $5.6 million to $44 million, depending on how many employees take it. The unions say the low figure is far more likely based on the number of workers that went on unpaid family leave in prior years.

Nov. 21 -- BART board expected to officially reject the family leave provision and send the contracts back to the unions for a new vote.