Put standalone recordings into their own one track release an expand release types to include the cases where currently standalone recordings are used.

From the wiki standalone recordings should be added for:

1. Internet-only release
This would be better to add as releasetype of 'IntenetDownloadOnly' or similar

2.Tracks captured from broadcast performance
This would be better to add as releasetype of 'TVBroadcast', 'RadioBroadcast; or similar

3.Pregap (track 0) tracks
Better served by supporting pregaps tracks in release

4.Multiple songs in one track
better served by supporting within release

Only 1> & 2> could even be considered 'standalone', and expanding release type would allow you to categorize these different standalone recordings.

We currently have 45,000 standalone recordings out of a total of 13.7M recordings, so they are not used very much but they do cause alot of problems for other applications because additional special handling has to be implemented for them, for example acoustid has this problem https://groups.google.com/forum/#!topic/acoustid/DMxnEfQ9vHQ . It also adds a load on the MusicBrainz search because to find them a search has to be done against the large recording index, whereas if they could be found in the much smaller release index it would take much less resource, and only require one search.