This page details the POSper build process/layout/structure using maven.
1) The root directory pom file delegates all the interesting build stuff to the plugins directory.
2) the plugins directory pom file simply enumerates the existing modules, including but not limited to core, where the interesting build stuff happens
The pom files for the various plugins have their own artifact id and name, but they share dependency on the maven-compiler-plugin (to compile themselves), maven-jpf-plugin (because they're all plugins), and maven-surefire-plugin (for testing) in their build/plugins section.
They also all use repo.posper.org and telscenter.org as their repositories, and repo.posper.org as their plugin repository.
The modules other than core are currently limited to build dependencies on jpf and the core plugin. This means that all the stuff they need to get their jobs done (eg, jasper.reports for the reports plugin) they access from what core integrates.
The core module has a whole laundry list of dependencies, many of which are strictly for the other plugins. The one dependency that makes it stand out as the foundation of POSper is the jpf-boot dependency, indicating that the core is needed to boot.