The Directory File `dir'
------------------------
For Info to work, the `info' directory must contain a file that
serves as a top level directory for the Info system. By convention,
this file is called `dir'. (You can find the location of this file
within Emacs by typing `C-h i' to enter Info and then typing `C-x C-f'
to see the pathname to the `info' directory.)
The `dir' file is itself an Info file. It contains the top level
menu for all the Info files in the system. The menu looks like this:
* Menu:
* Info: (info). Documentation browsing system.
* Emacs: (emacs). The extensible, self-documenting
text editor.
* Texinfo: (texinfo). With one source file, make
either a printed manual using
@TeX{} or an Info file.
...
Each of these menu entries points to the `Top' node of the Info file
that is named in parentheses. (The menu entry does not need to specify
the `Top' node, since Info goes to the `Top' node if no node name is
mentioned. Note:Nodes in Other Info Files.)
Thus, the `Info' entry points to the `Top' node of the `info' file
and the `Emacs' entry points to the `Top' node of the `emacs' file.
In each of the Info files, the `Up' pointer of the `Top' node refers
back to the `dir' file. For example, the line for the `Top' node of
the Emacs manual looks like this in Info:
File: emacs Node: Top, Up: (DIR), Next: Distrib
In this case, the `dir' file name is written in upper case letters--it
can be written in either upper or lower case. This is not true in
general, it is a special case for `dir'.