The following table has been extracted from the BPMN 2.0 standard where the rules to connect objects through message flows is defined.
"The arrow symbol indicates that the object listed in the row can connect to the object listed in the column. (...) Only those objects that can have incoming and/or outgoing Message Flows are shown in the table. Thus, Lane, Gateway, Data Object, Group, and Text Annotation are not listed in the table."
Business Process Model and Notation, v2.0 page 44