from the main Compilo document (compilo.sourceforge.net):
Often debugging is in org.compiere.model and org.compiere.process of this [the base] folder.
The model package also contains the Callout source codes, which should be the focus of any field level business logic.
The Process package houses most of the push-button process logic.
This folder is compiled into the CClient.jar with other folders and any changes to them
should only affect that jar.
Accounts process and posting actions are handled by the org.compiere.acct package
of the Server folder.Any changes there are compiled into the CServer.jar.
Some insight into other code folders are touched on by Marco in earlier chapters such as the one on Jasper Integration. Marco also touched on Ant Build.
"Sorprenderse, extrañarse, es comenzar a entender."
-- José Ortega y Gasset