GNU Emacs Lisp Reference Manual

28.4: Information from Markers

This section describes the functions for accessing the components of a marker object.

Function: marker-position marker

This function returns the position that marker points to, or nil if it points nowhere.

Function: marker-buffer marker

This function returns the buffer that marker points into, or nil if it points nowhere.

(setq m (make-marker))
     => #
(marker-position m)
     => nil
(marker-buffer m)
     => nil
(set-marker m 3770 (current-buffer))
     => #
(marker-buffer m)
     => #
(marker-position m)
     => 3770

Two distinct markers are considered equal (even though not eq) to each other if they have the same position and buffer, or if they both point nowhere.