OpenMG is an SDMI-compliant
digital rights management scheme by Sony. It is designed for audio files in ATRAC3 format. The compliant software, eg. Sony SonicStage, is usually capable of transcoding MP3 and wav files to OpenMG/ATRAC3. The file extensions OpenMG-encrypted files are .omg and .oma.
OpenMG modules also tend to choke on corrupted MP3 ID3 tags.
With some Sony portable audio players it is not possible to directly drag and drop the desired tracks to the device's directory structure, but a considerably cumbersome process of using Sony's own or compatible software must be undergone.