This is an example of how YANG's submodules can be used to structure a somewhat larger module into logical units. The example is the configuration of a set of services on a Linux-based networking device. There is a master module and a set of submodules:
execd.yang: The master module which defines the namespace and includes all submodules
execd-types.yang: A submodule which contains reusable types. Several other submodules include this one.