OS X‘s Time Machine backup system has an API that let application developers indicate that certain folders belonging to the application should be excluded from the user‘s backup. This is done through an extended attribute set on the directory in the file system.
With the mission statement “[…] [Déjà Dup] hides the complexity of doing backups […]” I kind of expect there to be such a thing. As an application’s developer should be well suited to know what folders are safe to exclude. But I cannot find any mention of it online.
Nudges in the right direction or to the right feature request would be appreciated.