A variety of data items, called element directions, are associated with element units. They may be used in the formatting functions, and/or associated with a button (see Simple Navigation Panel Customization).
Each element direction has a name and a reference to the element unit they
point to, when such an element exists. The element is either a
global element unit (for example, the Top element) or relative to the
current element unit (for example, the next element unit). Such relative
elements are determined with respect to the document structure defined
by the section structuring commands (@chapter,
@unnumbered…) or by the nodes if the node pointers are
specified on @node lines or in menus (see Two Paths in Texinfo).
Here is the list of global element units directions:
An empty button.
Top element.
About (help) page.
Table of contents.
Overview: short table of contents.
Corresponds to the Footnotes element (see Output Element Units).
The first element unit with @printindex.
Here is the list of relative element units directions:
The current element unit.
Next element unit in reading order.
First element unit in reading order.
Last element unit in reading order.
Previous element unit in reading order.
Next chapter element unit.
Beginning of this chapter, or previous chapter if the element is a chapter.
Next section element unit at the same level.
Previous section element unit at the same level.
Up section.
Next element unit in section reading order.
Previous element unit in section reading order.
Up in section reading order.
Next node element unit.
Next node element unit in node reading order.
Previous node element unit in node reading order.
Previous node element unit.
Up node element unit.
Relative direction elements are each associated to a variant, with
‘FirstInFile’ prepended, which points to the direction relative
to the first element in file. For example, FirstInFileNodeNext
is the next node element relative to the first element in file. The
‘FirstInFile’ directions are usually used in footers.