+In many cases, a combination of both methods is needed: some resources
+are marked as temporary, while some others are permanent. When the
+an operation is completed successfully (and @rp_commit() is called),
+all temporary resources are freed and the permanent ones detached.
+When the operation fails, @rp_delete() deletes all resources. By default,
+all resources are created as temporary. You can make a resource permanent
+by calling @res_permanent(), or change the default in `resource->default_res_flags`.
+