.. _topics-overlays:
*******
Overlay
An overlay is a collection of functions that provide an interface to command creation.
There are currently four (4) general and re-usable overlays:
- common
- django
- pgsql
- posix
And two (2) overlays that are specific to operating systems:
- centos
- ubuntu
The examples that follow instantiate command instances from an INI file. Each example is shown with the defaults. All commands support a number of :ref:`topics-configuration-common-parameters`.
.. include:: _includes/overlays.rst
