Union officials at the Library of Congress will not have to keep a list of the employees they talk to, after an impartial panel rejected the Library’s request for them to do so.

The ruling ends a yearlong dispute over how the LOC Professional Guild should report its activities to Library management. The stalemate made its way through every possible mediator, arbitrator and panel — the Federal Service Impasses Panel was the last possible stop.

Still, union officials will have to give the Library more detail on their activities during work hours. The terms will be plucked from the union’s proposal to the impasses panel and will be included in its bargaining agreement with the Library.

It’s taken months, but union leaders are finally claiming victory.

“We’re angry that we had to go through this. This has been a very difficult year, and none of this should have happened but it has,” said Kent Dunlap, the guild’s chief negotiator. “But we’re certainly happy with the outcome.”

The Library doesn’t plan to reopen the contract in April, when it is up for renewal, Library spokesman Matt Raymond said in an e-mail response.

The impasses panel’s decision also cannot be appealed.

“We are pleased that, with this dispute resolved, the Guild and the Library will be able to direct our resources collaboratively to the challenges facing the Library and its staff in the coming years,” Raymond wrote in an e-mail.

Union officials will now have to follow strict guidelines when reporting their activities during work hours — guidelines proposed by the union itself. There is only one difference: The impasses panel removed a a provision that would have allowed union officials to be less detailed about their activities if they took less than four hours a day.

The impasses panel’s decision comes as somewhat of a surprise.

When the Library first asked the panel to intervene, Raymond expressed confidence that it would rule in the Library’s favor. The union also worried that the panel was unfavorable to unions and decried the Library’s move.

But in the end, the union “got a very fair hearing,” said Nan Ernst, the union’s chief steward.

The disagreement began in the fall of 2006. For years, the union had reported its activities during work hours with descriptors such as “discuss complaint” and tallied the total hours used. But the Library wanted the descriptions to be more detailed, and it has been fighting for this added specificity for more than a year. Such detail, the Library has argued, would allow management to determine whether union officials are spending a “reasonable” amount of time on union activities. After all, the Library pays their salaries, whether its employees are doing Library or union work.

The LOC filed a grievance last fall, but an arbitrator struck it down in July. So the Library and union officials began reworking parts of the bargaining agreement.

In the Library’s proposal to the impasses panel, officials requested that the guild give a unique number to every employee that meets with the union. These numbers would be used on the forms reporting those meetings; for example, “preparation of Employee 1001 grievance.” The union would only have to disclose the employees’ names if the Library inspector general launched an investigation.

Union officials called this “union busting” and fought to keep employees names off any list. With the impasses panel’s decision, they will have to report only the subject matter and nature of their meetings with more detail.

Raymond said in his e-mail that the Library and union were close to agreeing to the same terms before the impasses panel’s decision. An internal memo from Inspector General Karl Schornagel already had noted that the reporting “need not include any identifying information for the individual involved.”

“The new language gives the Library more specificity in official time reports than we are getting today, and more than the union offered in its final offer,” Raymond said. “Although we would have preferred to get even more detail in official time reports, our Inspector General has advised us that the new language is adequate to satisfy the concerns he raised in a report that led to the dispute in the first place.”