texinfo-update-menu-higher-regexps

texinfo-update-menu-higher-regexps is a variable defined in `texnfo-upd.el'.
Its value is

((1 . "^@node [ 	]*DIR")
 (2 . "^@node [ 	]*top[ 	]*\\(,\\|$\\)")
 (3 concat "\\(^@\\(" texinfo-chapter-level-regexp "\\)\\>[ 	]*\\)")
 (4 concat "\\(^@\\(" texinfo-section-level-regexp "\\|" texinfo-chapter-level-regexp "\\)\\>[ 	]*\\)")
 (5 concat "\\(^@\\(" texinfo-subsection-level-regexp "\\|" texinfo-section-level-regexp "\\|" texinfo-chapter-level-regexp "\\)\\>[ 	]*\\)"))

Documentation:
Regexps for searching for higher level sections in a Texinfo file.
The keys are strings specifying the general hierarchical level in the
document; the values are regular expressions.