A Part is a Connectable Element that is an element of the structure of a Composite. A Composite is a Classifier which has an internal structure. It specifies the connections of individuals that are all related to the same other individual (M0). For example, a company type specifies the connections of departments within each individual company of that type (assuming it is modeled in a value chain manner, rather than just an organization chart). Likewise, an orchestration type specifies the sequence of steps in each individual occurrence of that orchestration. A Typed Part is a kind of Part that specifies that individuals playing the Part in the Composite must be of a certain kind (Type). For example, an individual playing the president part must be a person, and must play the president within a individual company . Typed Part is a Property for restricting the number of individuals that play the part. For example, a company might allow no more than five vice-presidents, but require a president, and a choreography might have an interaction that is optional. A Part Connection is a Feature of a composite used to connect its Connectable Elements. A Part Connection can connect any number of parts. For example, a business interaction can involve multiple companies. When a Part Connection is connecting Typed Part, its specifies links between M0 entities playing the typed parts. For example, the reporting connection between the president of a company and the CEO means the person playing the president in a particular company will report to the person playing the CEO in the same company. Likewise, the temporal connection between one step and another in a process means that in each occurrence of that process, there is an occurrence of one step that happens after the occurrence of another. Conditions may be applied to Part Connections to limit when they apply. For example, one step in a process may happen after another only when certain conditions are true as the process is executing. A Directed Part Connection is a kind of Part Connection for only two parts, when it is convenient to have standard names referring to the parts on each end (source and target). Directed Part Connections are designed to facilitate traversal of Part Connections . Their source and target associations specify the top-level parts (not Part Paths) that are connected, as typically shown by the arrows in process diagrams. For example, when one step is after another in a process, the arrow between them is modeled as a directed connection, with the earlier step at the source part, and the later step at the target part. Connectable Element is the subject of relations between parts through Part Connection. Connectable Element is a capability shared by Part and Part Path. Individuals playing parts can have any relation to the whole, they are not necessarily "contained", "owned", or "part of" the whole. A Part Path connects to a Part of a nested Composite. An instance of Part Path is introduced for each traversed part to a target part . The purpose of Part Path is to provide access to parts in a nested composite structure. All models based on the composition model needs to have access to parts within parts, for example; . Data elements within data elements . Roles within roles . Protocols within protocols . Activities within activities Part Path and Part are generalized to Connectable Element, which are the is of Part Connection. This enables connections not requiring part paths to refer directly to parts, rather than to part paths with only one element. An Irreflexive Condition is a kind of Opaque Condition that restricts the connection to apply at M0 only to distinct M0 individuals playing the part (or playing the last part in the path). It applies only to connections between Typed Parts, or Part Paths with at least one Typed Part. A Part Replacement is used to specify the replacement or removal of Parts in derived to Composite of a Derivation. A Part Group is a kind of Connectable Element that collects other Connectable Elements together. A Part Groups can share Connectable Elements. The meaning of part groups is given in the specializations of the Composition Model, for example, in Behavior Model. A Individual From Set is a kind of Selector Specification that provide a list of Individual as the potential Type of a Typed Part Individual instance A Selector Specification is a query mechanism used to specify the individuals playing a Typed Part The Parts of the derived to Composite are the same as the on derived from Composite, except for replaced or removed Parts, as specified by derivation trace , or added parts.