What watches “:has” what?

Is there some place that lists what watches have specific “has:" capabilities? 

For example:

myVariable = (Toybox has :onPartialUpdate);
myVariable = (Toybox has :Complications);
You’d think these would be listed in the Toybox under WatchUi, WatchFace…. I cannot find them.  The compatible devices list some info, but not this info.
Thanks
Jeff