How would you specify whether a new role you've created can delete items or not (1.3.*)? all of the dselete related stuff in permissiondefinitions.xml seems to have been commented out.
The only things that are commented out would enforce that you had certain rights on parents and children.
Currently delete does not check you have delete for all the children. This can be added in the config but is a big performance overhead. (You can require a permission on each child for delete - which will end up being a condition on all children at any depth)
This file is found by path - but it can be set in the config. If you use the extension directory to over-ride the permissionsModelDAO bean (in public-services-security-context.xml) you can set where the model definition file is loaded.