What is the meaning of AppResourceTrackingSettings

I am reading this documentation from Microsoft

http://msdn.microsoft.com/en-us/library/microsoft.sharepoint.administration.spwebapplication.appresourcetrackingsettings.aspx

The only explanation Microsoft provides for this setting on the web app is

"Per-app resource tracking settings."

Now this points to a class called SPResourceTrackingSetting.

http://msdn.microsoft.com/en-us/library/microsoft.sharepoint.administration.spresourcetrackingsettings.aspx

And here also the documentation only has a one liner

"Settings controling resource tracking."

Wow Microsoft ... just one line ...you serious ... ???

Here is what I am see in powershell.

Does anyone know what these things do? My understanding is that apps are javascript so what throttling is being done on apps?

val it: unit=()