compx description for a call graph

gistfile1.xml

<components  gutter="50" top="50" left="50" gc="steelblue">
	<comp id="io"		name="io"  row="0" col="1" width="120" height="40" shape="plain">
		<connect mark="d" dest="errors" sloc="e" dloc="w"/>
		<connect mark="d" dest="sync"   sloc="s" dloc="n"/>
	</comp>
	
	<comp id="errors"	name="errors" row="0" col="2" width="120" height="40"  shape="plain"/>
	
	<comp id="sync"		name="sync"	  row="1" col="1" width="120" height="40"  shape="plain">
		<connect mark="d" dest="sa" sloc="w" dloc="n" dir="ccw"/>
		<connect mark="d" dest="runtime" sloc="e" dloc="n"/>
		<connect mark="d" dest="unsafe" sloc="s" dloc="n"/>
	</comp>
	
	<comp id="sa"		name="sync/atomic"	row="2" col="0" width="120" height="40"  shape="plain">
		<connect mark="d" dest="unsafe" sloc="s" dloc="w" dir="ccw"/>
	</comp>
	
	<comp id="runtime"	name="runtime"		row="2" col="2" width="120" height="40"  shape="plain">
		<connect mark="d" dest="unsafe" sloc="s" dloc="e"/>
	</comp>
	<comp id="unsafe"	name="unsafe"		row="3" col="1" width="120" height="40"  shape="plain"/>	
</components>