The folks at the MBTA are all about transparency these days, but on some issues they are as secretive as ever. One of those issues is the contract negotiations with the union representing about 400 of the T’s management level employees.

Neither union nor T officials would discuss what happened, but sources say the original contract language, which included a no-layoff clause, angered the MBTA’s oversight board. Board members apparently were so upset with the language that they rejected the contract and reprimanded the T’s two negotiators, general manager Frank DePaola and Kimberly Poirier, the director of labor relations. Both DePaola and Poirier have since left the T.

A revised contract without the no-layoff clause was approved by the Fiscal Management and Control Board by a 3-1 vote on June 20. Lisa Calise, the lone no vote, said her chief concern was about giving the managers a higher salary increase than other unions and leaving the T on the hook for $963,000 in salaries that hadn’t been budgeted.

While that vote took place in public after almost no debate, sources say the real action took place behind closed doors over the previous months when the control board was meeting in executive session. T officials said they would not comment on meetings in executive session or personnel matters.

The contract negotiations were with Local 453 of the Office and Professional Employees International Union, which represents T managers. At a press conference on Wednesday, Transportation Secretary Stephanie Pollack said there are two types of managers at the T: those who report directly to the general manager and can be fired at will, and and those who are unionized.

Pollack said the number of nonunion managers has fallen precipitously in recent years, to less than 200. She indicated that it’s not easy dealing with unionized managers at an agency where most of the employees are union members. “This is a challenge for the T to work with those folks who are both unionized and managers at the same time,” she said.

Local 453 officials did not return phone calls and emails, but on the union’s website are a number of posts about the contract negotiations. One from May 5 said the union ratified a new, three-year contract covering the period from July 1, 2015, through June 30, 2017. The contract called for a wage increase of 2.5 percent the first year and 3.5 percent the second and third years.

The contract also included a side letter agreement stating that the “MBTA agrees that no member of the bargaining unit represented by OPEIU Local 453 shall be laid off for a period of one year from the date of signing of this agreement.”

In a post on May 19, union officials reported to the membership that the Fiscal Management and Control Board had rejected the agreement with the no-layoff side letter “even though we had been told before our ratification vote that the FMCB had reviewed the [agreement] several weeks prior to our ratification meeting and had approved its terms in executive session.”

Another post said union officials resumed their negotiations with T officials with the no-layoff side letter off the table. With minimal other changes, the contract was approved again by the union on June 14 and by the Fiscal Management and Control Board six days later. At the control board meeting, there was no mention of the no-layoff clause; the T’s legal counsel called the contract’s higher pay increases in the second and third years “unique” and said the agreement should not be construed as setting a new pattern for contracts beginning in fiscal year 2019.

A June 10 post on the union website, under the headline “correction,” referred to an earlier post in which the union said it “had been informed that the general manager of the MBTA and the director of labor relations had withheld information about the union’s ‘no layoff’ side letter agreement. We have since been told by the director of labor relations that this statement about withholding information about the no layoff side letter was not accurate and we apologize for any misunderstanding.”

The union’s earlier post could not be found. It was unclear who the information about the no layoff side letter was withheld from, but it appeared to be a reference to the Fiscal Management and Control Board.