In a move that would mark the end of a digital music era, Sony BMG Music Entertainment is finalizing plans to sell songs without the copyright protection software that has long restricted the use of music downloaded from the Internet, BusinessWeek.com has learned.

According to the report, Sony BMG will make at least part of its collection available without so-called digital rights management, or DRM, software some time in the first quarter, said "people familiar with the matter."

This means that all four majors have begun to abandon DRM. Stores like Amazon and the iTunes Store "iTunes Plus" section let customers buy music online, by the track, that they can play on any mobile device, portable MP3 player, or computer.