Final Realms uses properties heavilly. These are tags on objects/rooms/players that determine how other things will interact with them. They affect things like spell damage, unburied corpses coming to life and other "cute" stuff. In general coders should NEVER use add_property(), however add_timed_property() and add_static_property() are reasonably safe to use. In terms of priorities. timed over-rides static which over-rides "normal" permanent properties.