The default HTML output is a file for each of the source files with one extra file ``cxref.html'' that includes each of the other files. This is to allow a makefile to only update the changed files (although the references may require all of the files to be checked again). When the cxref.html file has been written it can be modified by the user, any new files that are added are added at the end before the table of contents, the rest of the file being unchanged.
The index is written to a file called ``cxref.apdx.html'' and cxref.html is updated to refer to it.
(The file names ``cxref.html'' and ``cxref.apdx.html'' are different if the ``-N'' option is used.)