Salt includes a number of built-in subsystems to generate top file data, they are listed listed at Full list of builtin master tops modules.
The source for the built-in Salt master tops can be found here: https://github.com/saltstack/salt/blob/develop/salt/tops
Docs for previous releases are available on salt.rtfd.org.
Latest Salt release: 2014.7.2
22.30. Full list of builtin master tops modules
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