AppGranule
An AppGranule represents a particular application - e.g. Adobe InDesign, Illustrator, QuarkXPress...
AppGranule normally don't roam the data flow. Instead they represent the application that's hosting the current Crawler conversion.
The AppGranule provides an easy 'repository' for application-specific data.
The AppGranule also provides easy access to some services for the Crawler software: it provides program code to create new 'top level' granules (e.g. DocumentGranule).
Another function of the AppGranule is to serve as the 'parent granule' of all 'top level' granules.
Normally, there is only a single AppGranule for the current Crawler session.
E.g. when running an InDesign-to-something conversion, the 'host' application will be InDesign, and there will be a single InDesignAppGranule available.
