Represents the "CO" entry of the sound object stream object.

It is an optional entry defined as part of the PDF 1.0 specification.

It contains a string representing a PDF name object.

For definitive details see:.

The ISO PDF Specification, ISO 32000-1:2008 PDF 1.7; Table: 294, page 507.

The ISO PDF Specification, ISO 32000-2:2017 PDF 2.0; Table: 305, page 634.

The CO entry names the compression codec for the audio data when a non-standard encoding is used. This name identifies the codec to the media player.