while systems in which the majority of things are physical shall be primarily physical. The default value of the Essence generic attribute of a thing in a primarily informatical [physical] system shall be informatical [physical]. Object states Stateful and stateless objects Dov Dori explains in Model-Based Systems Engineering with OPM and SysML that "An object state is a possible situation in which an object may exist. An object state has meaning only in the context of the object to which it belongs." A stateless object shall be an object that has no specification of states. A stateful object shall be an object for which a set of permissible states are specified. In a runtime model, at any point in time, any stateful object instance is at a particular permissible state or in transition between two states. Attribute values An attribute is an object that characterizes a thing. An attribute value is a specialization of state in the sense that a value is a state of an attribute: an object has an attribute, which is a different object, to which that value is assigned for some period of time during the existence of the object exhibiting that attribute. Object state representation A state is graphically defined by a labelled, rounded-corner rectangle placed inside the owning object. It can not live without an object. In OPL text, the state name shall appear in bold face without capitalization. Initial, default, and final states Initial, final, and default state representation A state that is initial is graphically defined by a state representation with thick contour. A state that is final is graphically defined by a state representation with double contour. A state that is default is graphically defined by a state representation with an open arrow pointing diagonally from the left. The corresponding OPL sentences shall include explicit indicators for an initial, final or default state. Links Procedural links A procedural link is one of three kinds: Transforming link, which connects a transformer (an object that the process transforms) or its state with a process to model object transformation, namely generation, consumption, or state change of that object as a result of the process execution. Enabling link, which connects an enabler (an object that enables the process occurrence but is not transformed by that process) or its state, to a process, which enables the occurrence of that process. Control link, which is a procedural