We got a few general music player icons for playing and manipulating playlists.
> = play tune >> = hold to move backwards in tune (or skip to next tune) << = hold to move forward in tune (or skip to prev tune) || = pause >>| = skip one tune forward and play <<| = skip one tune back and play >| = add to the end of queue?
The last icon is little bit vague and is not used that much. I thought it meant play tune at end of playlist. I tried to find information of the button on the internet and even if it is used a lot in icon sets there isn't any information on the use of it.