msc {
	hscale="2";
	ue [label="UE"], nodeb [label="NodeB"], rnc [label="RNC"], cbc [label="CBC"], cbe [label="CBE"];

	cbc <= cbe [label="New message (duration, geographic scope)"];

	cbc box cbc [label="Determine list of RNCs in scope"];
	rnc <= cbc [label="SABP WRITE-REPLACE"];
	rnc => cbc [label="SABP WRITE-REPLACE ACK"];

	rnc box rnc [label="Determine list of NodeBs in scope"];
	rnc box rnc [label="Schedule with any other SMSCB for give NodeBs"];

	nodeb <= rnc [label="CTCH RRC CBS"];
	ue <= nodeb [label="CTCH RRC CBS"];
	rnc box rnc [label="flow control; scheduling"];
}