XORP is a simple planer that can plan tasks and compute the level of use of resources. Its particularity is to take into account 2 kinds of "nodes" between tasks, i.e. AND node that are usual in planing software (TaskA then TaskB1 AND TaskB2) and XOR node that can show alternative between several branches of the project graph (TaskA then TaskB1 OR TaskB2). A seaside test interface can be found at http://atlas.seasidehosting.st