Yet as the Internet music services approach the end of one negotiating marathon, they are discovering that they are only at the beginning of the race to stock their digital shelves.

The "B's" for instance, look pretty bare without the Beatles, Garth Brooks and the Beach Boys. Their label, EMI, has so far not reached an agreement to distribute their work over the Internet. A label may not own the sound recording rights for imported CD's, or those that they distribute for smaller labels. And a track that uses "samples" from other songs — as the majority of hip-hop recordings do — can require renegotiating royalty rates with dozens of copyright holders before it can be delivered digitally.

Larry Kenswil, the president of the eLabs division of Universal Music, said that obstacles to clearing the rights for samples will prevent the company from offering several songs when it begins selling tracks from its own catalog online this fall. "It's a nightmare," Mr. Kenswil said.

....Meanwhile, at the online music services, which are trying to fashion a business based on respecting the copyrights of all of the constituencies, some progress is being made.

"When we cleared David Bowie and Pink Floyd I was turning cartwheels," John Jones, the chief of content acquisition for MusicNet, said one recent morning as he reviewed a list of 1,700 tracks that were set to go up on the service. It was an eclectic mix of songs from Al Green, Blind Melon, Crowded House, Roxy Music, the O'Jays and Kiri Te Kanawa, the soprano, performing "Greensleeves."

"You can't rest until everything is cleared," Mr. Jones said. "They're all fantastic to have. You want every recorded song."