Since the reST source files can have different extensions (some people like .txt, some like .rst -- the extension can be configured with :confval:`source_suffix`) and different OSes have different path separators, Sphinx abstracts them: all "document names" are relative to the :term:`documentation root`, the extension is stripped, and path separators are converted to slashes. All values, parameters and suchlike referring to "documents" expect such a document name.
The TOC tree
Since reST does not have facilities to interconnect several documents, or split documents into multiple output files, Sphinx uses a custom directive to add relations between the single files the documentation is made of, as well as tables of contents. The toctree directive is the central element.
Sphinx reserves some document names for its own use; you should not try to create documents with these names -- it will cause problems.
The special document names (and pages generated for them) are:
genindex, modindex, search
These are used for the general index, the module index, and the search page, respectively.
The module index contains one entry per :dir:`module` directive.
every name beginning with _
Though only few such names are currently used by Sphinx, you should not create documents or document-containing directories with such names. (Using _ as a prefix for a custom template directory is fine.)