Legislation to allow unmarried Pittsburgh couples -- straight or gay -- to register their relationships with the city seems well on its way to becoming law, after getting tentative approval from city council and Mayor Luke Ravenstahl's support yesterday.

"I think it shows that we are much more forward-thinking than people might think we are," said Councilman Bruce Kraus, who along with Council President Doug Shields was the prime author of the measure. He said 72 cities have similar registries.

"Once the legislation gets here, I'll probably sign it," said Mr. Ravenstahl, adding that it still requires a Law Department review. "Conceptually, I'm supportive of it."

Only Councilman Ricky Burgess voted against the legislation, which allows any two city residents -- unless they are too closely related to be married -- to show documentary evidence of their "mutual commitment," pay $25, and be registered.

If one is a city employee, then the couple would immediately become eligible to share benefits. The city has long offered benefits to domestic partners and common law spouses of its employees, but the new legislation tightens up definitions.

The city now provides benefits to common law spouses of 55 employees, and domestic partners of another five, according to Personnel Director Barbara Trant, whose department would administer the registry.

Other employers would not be required to honor the domestic registrations, but could opt to use that certification as a criterion for sharing benefits.

Acting on the advice of the Law Department, council added language disallowing non-city residents from registering. That was done to reduce the likelihood of a challenge in court or in the General Assembly.

A final vote is set for Tuesday. It would then go to the mayor for his signature, and then become effective as soon as the Personnel Department could set up procedures.