A process definition consists of a unique name and a set of nodes. The nodes are connected via arcs. Every process definition must have at least one node. If a process definition contains no nodes with the isStart attribute set to true, it can not be run on it's own. This is still valid however, since it could be referenced from another process definition. Every process definition may contain contain zero or more references to external process definitions. Every process definition must have a unique name. Node names must be unique within a given process definition. If isStart is set to true, this node will have a token placed in it. Guard functions will still be called for start nodes. Since it may be desirable to include the same external process definition more than once, each external must define a name which must be unique in the process definition. Must refer to a valid process definition name. Contains a GuardLang statement Join strategies may require additional information, which can be provided in the join parameter. This may include things like a token set name or a JoinLang program Name of the node in the this external process definition that this arc will start from Specifies the instance name of the external process definition that is being linked to. The latest version of the external process definition will be used. If this is not specified, it is assumed that we are linking to a node in the surrounding process definition. Name of the node in the specified external process definition that this arc will connect to The arc name. Does not need to be unique. Arcs with the same name are considered to be part of a set.