Two long-simmering issues that affect the future of Metro's planned subway line through Anacostia and into southern Prince George's County officially were resolved by the Metro Board Yesterday.

The actions clear the way for Metro to proceed with long-delayed design and planning work prior to construction on the Green Line, which is scheduled to open to the Anacostia Station in mid-1985.

The rest of the line into Prince George's County at Rosecroft Raceway would open late in 1986, although Metro is circulating a financial proposal that would accelerate that date by one year.

The board yesterday authorized construction of a 1,300-car parking lot at the Anacostia Station and officially designated Rosecroft as the Green Line's southern terminus. Both actions were preeceded by controversy.

The parking lot was opposed by Anacostia residents as an infringement on their community. Through a series of meetings between District of Columbia officials and area residents, the problems with the parking were resolved.

The Green Line to Anocosita will come from the the existing L'Enfant Plaza station, then turn east under M Street and proceed through the Navy Yard before turning to cross the Anacostia River in tunnels. From the Anacostia Stations, the line will go through St. Elizabeths Hospital, then proceed south generally along Wheeler Road to the terminal near the present Rosecroft Raceway.

On early Metro maps, the Green Line was supposed to go from the Anacostia station out the Suitland Parkway and ultimately terminate at Branch Avenue and Auth Road.

The alignment was changed 18 months ago after a regionwide restudy of the uncompleted Metro lines and at the insistence of the Prince George's County Council. Opposition of citizen groups in the county to that change has been intense, however, and may continue, officials conceded privately yesterday.

A change in alignment is not official, however, unitl the Metro Board formally redraws its map. That is what happened yesterday.