To use auto-overlays in an Elisp package, you must load the overlay classes that you require by including lines of the form
(require 'auto-overlay-class)
near the beginning of your package, where class is the class
name. The standard classes are: word, line, self,
nested and flat (see Overview), though new classes can
easily be added (see Extending the Auto-Overlays Package).
Sometimes it is useful for a package to make use of auto-overlays if any are defined, without necessarily requiring them. To facilitate this, the relevant functions can be loaded separately from the rest of the auto-overlays package with the line
(require 'auto-overlay-common)
This provides all the functions related to searching for overlays and
retrieving overlay properties. See Searching for Overlays. Note that
there is no need to include this line if any auto-overlay classes are
required, though it will do no harm.
This section describes the functions that are needed in order to make use of auto-overlays in an Elisp package. It does not describe functions related to extending the auto-overlays package. See Extending the Auto-Overlays Package.