Streaminfo is a "standard" way of providing song info like title/artist/album/duration/artwork and more, along with the showname and location and any hints as to it being a live show or not.
The data is provided as JSON, and by this point I guess you can say the structure of the data is pretty much frozen. While new types of data might be added, no data will ever be removed (famous last words right?).
Two reasons for this, number one is that a standard must remain consistent to actually be a standard, and secondly it is now known to be used by others outside GSP (besides GridStream Webplayer, GridStream Player).
The longterm url for the streaminfo is player.gridstream.org/streaminfo/
but currently this just redirects to https://gsp.torontocast.stream/streaminfo/
Known projects making use of GridStream Streaminfo: