msc {
     SC [label="Simple OnOff Client"], SS [label="Simple OnOff Server"], N [label="Network"];
     SC -x SS [label="set: ON"];
     SC -> SS [label="set: ON"];
     SS -> SC [label="status: ON"];
     SS -> N [label="status: ON"];
     SC -> SS [label="set unreliable: OFF"];
     SS -> SC [label="status: OFF"];
     SS -> N [label="status: OFF"];
     SC -> SS [label="get"];
     SS -x SC [label="status: OFF"];
     SC -> SS [label="get"];
     SS -> SC [label="status: OFF"];
 }