+@node Properties in Mode
+@subsection Properties in the Mode Line
+
+ Starting in Emacs 21, certain text properties are meaningful in the
+mode line. The @code{face} property affects the appearance of text; the
+@code{help-echo} property associate help strings with the text, and
+@code{local-map} can make the text mouse-sensitive.
+
+ There are three ways to specify text properties for text in the mode
+line:
+
+@enumerate
+@item
+Put a string with the @code{local-map} property directly into the
+mode-line data structure.
+
+@item
+Put a @code{local-map} property on a mode-line %-construct
+such as @samp{%12b}; then the expansion of the %-construct
+will have that same text property.
+
+@item
+Use a list containing @code{:eval @var{form}} in the mode-line data
+structure, and make @var{form} evaluate to a string that has a
+@code{local-map} property.
+@end enumerate
+
+ You use the @code{local-map} property to specify a keymap. Like any
+keymap, it can bind character keys and function keys; but that has no
+effect, since it is impossible to move point into the mode line. This
+keymap can only take real effect for mouse clicks.
+
+@node Header Lines
+@subsection Window Header Lines
+@cindex header line (of a window)
+@cindex window header line
+
+ Starting in Emacs 21, a window can have a @dfn{header line} at the
+top, just as it can have a mode line at the bottom. The header line
+feature works just like the mode line feature, except that it's
+controlled by different variables.
+
+@tindex header-line-format
+@defvar header-line-format
+This variable, local in every buffer, specifies how to display the
+header line, for windows displaying the buffer. The format of the value
+is the same as for @code{mode-line-format} (@pxref{Mode Line Data}).
+@end defvar
+
+@tindex default-header-line-format
+@defvar default-header-line-format
+This variable holds the default @code{header-line-format} for buffers
+that do not override it. This is the same as @code{(default-value
+'header-line-format)}.
+
+It is normally @code{nil}, so that ordinary buffers have no header line.
+@end defvar
+