First there's the standard keyErrorNumber parameter, which returns an error code if delivery failed. The Macintosh has always had a drag and drop user experience, but the true power and generality of dragging has been widely recognized only recently. The drag paradigm can even be used for source control. DropShell takes care of the rigmarole of receiving this and other required Apple events. The ProjectDrag miniapplications pull the file specifications out of 'odoc' events and create SourceServer commands that operate on the files and folders that were dropped on their icons.
Some setup is required.
ProjectDrag needs to know the locations of Projector databases. It maps between project names and Projector database files by keeping aliases to database folders in its Preferences folder. To start using a project, simply drag its ProjectorDB file or the enclosing folder onto ProjectDrag Setup. Projector also needs to know your user name, and your initials or a nickname are used in change comments at the start of files. These are stored in a text file in the Preferences folder.