Follow the link to the new thread and read the first post. I quote to make it obvious to you:
"Developers: New "projectionType" variable available (in json format too) to identify 360° images"
That came too late, my implementation was ready at that time..
Before that post, in fact since the first post about photo spheres it was possible to get both the variable and its possible values just by adding a single variable to slide.htt. And that method is already documented.
You may have noticed that there has been no information in the forum posts on how the other 360º image settings are stored, and yet I managed to obtain that information from just using the jAlbum application and adding a rectilinear image to a project.
So all of the information needed was there from the start, you just needed to look for it.