At some point you will want to categorize your nodes in a sort of taxonomy / vocabulary, where each node could be part of multiple vocabularies.
"Rome" is a "City". But "Rome" is also inside "Italy".
As we are using a hierarchic file-system folders, apparently.
That's where symlinks (symbolic links) come handy!
Every file system allows linking one resource (file or folder) into another resource. This makes possible to have your nodes/folders included as a child of as many other nodes as you want, with just a link.
Of course, the "real" resource will only exist in one place; that's why, when designing a Quanta architecture, you should pay attention to the way you build and organize your node structure.
Using manager to categorize nodes
It would not be convenient for standard users to create symbolic links by hand (although that's definitely possible for some power users!).
That's why we included in Quanta a shadow component called "Manager", that provides the end user with a nice UI for content categorization.
To use the category manager, just include the manager_form component in your LINK|title=Shadow add forms:creating-and-editing-nodes-with-shadow].