In my work I typically encounter a task that is common to multiple projects. I haven't found any example of how to handle this in a GTD workflow. I use tags to note a task that is common to multiple projects, but would like the physical structure as well. Copying the same task into multiple project hierarchies doesn't make much sense to me as I would need to update the same task twice, unless there was some way to synchronize them. Does anyone have references or ideas about how to handle this?