texinfo: Node Menu Illustration

Nodes

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6.4 Node and Menu Illustration
==============================

Here is a copy of the diagram shown earlier that illustrates a Texinfo
file with three chapters, each of which contains two sections.

  The "root" is at the top of the diagram and the "leaves" are at the
bottom.  This is how such a diagram is drawn conventionally; it
illustrates an upside-down tree.  For this reason, the root node is
called the 'Top' node, and 'Up' node pointers carry you closer to the
root.

                              Top
                               |
             -------------------------------------
            |                  |                  |
         Chapter 1          Chapter 2          Chapter 3
            |                  |                  |
         --------           --------           --------
        |        |         |        |         |        |
     Section  Section   Section  Section   Section  Section
       1.1      1.2       2.1      2.2       3.1      3.2

  Using explicit pointers (not recommended, but for shown for purposes
of the example), the fully-written command to start Chapter 2 would be
this:

     @node     Chapter 2,  Chapter 3, Chapter 1, Top
     @comment  node-name,  next,      previous,  up

This '@node' line says that the name of this node is "Chapter 2", the
name of the 'Next' node is "Chapter 3", the name of the 'Previous' node
is "Chapter 1", and the name of the 'Up' node is "Top".  You can (and
should) omit writing out these node names if your document is
hierarchically organized (Note: makeinfo Pointer Creation), but the
pointer relationships still obtain.

     Note: 'Next' and 'Previous' refer to nodes at the _same
     hierarchical level_ in the manual, not necessarily to the next node
     within the Texinfo file.  In the Texinfo file, the subsequent node
     may be at a lower level--a section-level node most often follows a
     chapter-level node, for example.  (The 'Top' node contains the
     exception to this rule.  Since the 'Top' node is the only node at
     that level, 'Next' refers to the first following node, which is
     almost always a chapter or chapter-level node.)

  To go to Sections 2.1 and 2.2 using Info, you need a menu inside
Chapter 2.  (Note: Menus.)  You would write the menu just before the
beginning of Section 2.1, like this:

        @menu
        * Sect. 2.1::    Description of this section.
        * Sect. 2.2::    Description.
        @end menu

  Using explicit pointers, the node for Sect. 2.1 is written like this:

     @node     Sect. 2.1, Sect. 2.2, Chapter 2, Chapter 2
     @comment  node-name, next,      previous,  up

  In Info format, the 'Next' and 'Previous' pointers of a node usually
lead to other nodes at the same level--from chapter to chapter or from
section to section (sometimes, as shown, the 'Previous' pointer points
up); an 'Up' pointer usually leads to a node at the level above (closer
to the 'Top' node); and a 'Menu' leads to nodes at a level below (closer
to 'leaves').  (A cross reference can point to a node at any level; see
Note: Cross References.)

  Usually, an '@node' command and a chapter structuring command are
conventionally used together, in that order, often followed by indexing
commands.  (As shown in the example above, you may follow the '@node'
line with a comment line, e.g., to show which pointer is which if
explicit pointers are used.)  The Texinfo processors use this construct
to determine the relationships between nodes and sectioning commands.

  Here is the beginning of the chapter in this manual called "Ending a
Texinfo File".  This shows an '@node' line followed by an '@chapter'
line, and then by indexing lines.  The manual uses implictly determined
node pointers; therefore, nothing else is needed on the '@node' line.

     @node Ending a File
     @chapter Ending a Texinfo File
     @cindex Ending a Texinfo file
     @cindex Texinfo file ending
     @cindex File ending

  An earlier version of the manual used explicit node pointers.  Here is
the beginning of the same chapter for that case.  This shows an '@node'
line followed by a comment line, an '@chapter' line, and then by
indexing lines.

     @node    Ending a File, Structuring, Beginning a File, Top
     @comment node-name,     next,        previous,         up
     @chapter Ending a Texinfo File
     @cindex Ending a Texinfo file
     ...