Each task waits until it can be allocated a resource, so it can have at most one active request. Each request has a mode and a time limit. A task can own any number of resources. It owns each resource with a specific mode. The number of tasks that can own a resource depends on the mode.
Resources are either elementary resources or containers.
A container contains at least one resource. A resource can be contained in at most one container. Each task has a user who authorized the task. Each user has a name and a password. Each elementary resource has a cost.