A DecisionNode accepts tokens on its primary incoming edge and offers them to all its outgoing edges. However, each token offered on the primary incoming edge shall traverse at most one outgoing edge. Tokens are not duplicated. Source Unified Modeling Language 2.5.1
If the primary incoming edge of a DecisionNode is a ControlFlow, then all outgoing edges shall be ControlFlows and, if the primary incoming edge is an ObjectFlow, then all outgoing edges shall be ObjectFlows. Source Unified Modeling Language 2.5.1
If it has two incoming edges, then one shall be identified as the decisionInputFlow, the other being called the primary incoming edge. If the DecisionNode has only one incoming edge, then it is the primary incoming edge. Source Unified Modeling Language 2.5.1
