Ply has a concept of submodules which (like maven's aggregators) is simply a convenient way to allow one sequence of script invocations to be progagated to other subprojects during the same execution. Submodules are configured by placing the subproject directory name in a property file with context submodules. For instance if you had a project named mypoject which has a sub-directory named mysubproject which was also a ply project one could add
mysubproject as a submodule to myproject by invoking the following from within the myproject directory:
$ ply set mysubproject= in submodules
Then all ply scripts run for mypoject are also run for mysubproject; e.g.
$ ply clean install
Run from myproject will also run clean install on mysubproject.
One specifies a project as a submodule by using its directory name (which means that submodules need to be subdirectories of a project). Also, when adding a submodule to the submodules.properties file the property value is ignored and so can be anything; convention dictates that it is "".