The unit of information is typically the HTML page, which is uploaded to the server and usually linked to other pages. These links are simple references to the location of the other document, and if that document is moved or erased, a link to nowhere remains. Hyperwave has a number of features which help to alleviate these problems. Collections and clusters help you to organize information, and Hyperwave's links are automatically removed when the object being referred to is removed, guaranteeing link consistency. It may help to think of collections as being analogous to a file system with directories which contain files as well as other directories.
Collections use the same hierarchical structuring of information as directories do.
Collections and documents can be added and removed, and also moved freely from one collection to another, the only restriction being that a collection may not belong, either directly or indirectly, to itself. It is also possible to copy collections, in which case they will appear to be physically present in more than one collection. They are, however, only linked, which means that only one actual physical copy exists on the server and the different collections all refer to it. This detail doesn't matter if you are just looking at the collections, however, if two people each copy a collection for their own use and each intends to alter it to suit his or her needs, it won't work. Things are done this way so that users cannot simply duplicate existing information arbitrarily often and cause the server to run out of space.