"Hidden Tracks" aren't are not meaningful for online trading and DDEX recommends to not use themthat they should not be used.
However, when a physical album is being digitised and made available in an online environment, it may be necessary to handle hidden tracks. There are two principle approaches that can be taken:
The sound recording that is hidden on the physical album will should be listed alongside the other tracks of the album in a separate
SoundRecording composite. As a consequence, there will be a separate audio file for the Resource that formerly-hidden Resourcewas hidden on the physical album.
This is the preferred approach.
If the record company determines that a sound recording must remain hidden, it needs to amalgamate the hidden
with a "normal" (i.e. visible) with a visible sound recording.
In that case there will be one
SoundRecording composite with the title of just the normal trackvisible sound recording.
However, when identifying this amalgamated this sound recording, now amalgamated with the hidden sound recording, it will be necessary to allocate a separate different and unique ISRC from the one used for just the normal originally allocated to the visible sound recording. And whether the SoundRecording Whether or not the SoundRecording [should be Courier] composite for the visible sound recording now amalgamated with the hidden sound recording should recording should contain contributors for both sound recordings will be left to the record company marketing the digitised album.
There will also be a Resource file that will contain the audio of one normal sound the visible sound recording plus the audio for the hidden sound recording.
This approach has the drawback that the DSP receiving such a digitised album may not be aware that there is a "hidden" recording and a "hidden" musical work involvedwork contained in the file.