+(defcustom org-agenda-day-face-function nil
+ "Function called to determine what face should be used to display a day.
+The only argument passed to that function is the day. It should
+returns a face, or nil if does not want to specify a face and let
+the normal rules apply."
+ :group 'org-agenda-line-format
+ :type 'function)
+
+(defcustom org-agenda-category-icon-alist nil
+ "Alist of category icon to be displayed in agenda views.
+
+Each entry should have the following format:
+
+ (CATEGORY-REGEXP FILE-OR-DATA TYPE DATA-P PROPS)
+
+Where CATEGORY-REGEXP is a regexp matching the categories where
+the icon should be displayed.
+FILE-OR-DATA either a file path or a string containing image data.
+
+The other fields can be ommited safely if not needed:
+TYPE indicates the image type.
+DATA-P is a boolean indicating whether the FILE-OR-DATA string is
+image data.
+PROPS are additional image attributes to assign to the image,
+like, e.g. `:ascent center'.
+
+ (\"Org\" \"/path/to/icon.png\" nil nil :ascent center)
+
+If you want to set the display properties yourself, just put a
+list as second element:
+
+ (CATEGORY-REGEXP (MY PROPERTY LIST))
+
+For example, to display a 16px horizontal space for Emacs
+category, you can use:
+
+ (\"Emacs\" '(space . (:width (16))))"
+ :group 'org-agenda-line-format
+ :type '(alist :key-type (string :tag "Regexp matching category")
+ :value-type (choice (list :tag "Icon"
+ (string :tag "File or data")
+ (symbol :tag "Type")
+ (boolean :tag "Data?")
+ (repeat :tag "Extra image properties" :inline t symbol))
+ (list :tag "Display properties" sexp))))
+