The original metadata format was ID3 and this defined a field called Grouping that was intended to be used to store the work for Classical music, but it also had other uses, it was defined as
“The 'Content group description' frame is used if the sound belongs to a larger category of sounds/music. For example, classical music is often sorted in different musical sections (e.g. "Piano Concerto","Weather - Hurricane”"
This definition is a bit open to interpretation so over the years the field has been used by different applications in different ways, both as a work and as a way to group multiple tracks in other ways. For example in SongKong it can be used to store genres as a list of values because iTunes Genre can only see the first value, a problem if you want to categorize a song with multiple genres.
So SongKong uses a separate Work field to store the work, but depending on what audio formats and what audio players you are using you may want to copy the contents of the Work field to the Grouping field. So for example iTunes uses the Grouping field to store the work for formats that use ID3 such as MP3 and AIF, but it has a separate Work field for MP4 and M4A files, and this is the same as the Work field that SongKong uses for this format.
If you are using Flac/Ogg your player may expect works to be stored in the Grouping field or the Work field or have no support at all for works
So we provide the following options for this option:
No
Yes
MP3 and AIF (iTunes)
All audio formats except MP4