digraph G {
    margin=0;
	{
	rank=same;
    s [style=bold, label="before"];
	}
	
	{
	rank=same;
    a [label=<<FONT COLOR="red">M</FONT>>,fontname=helvetica];
    p [label=<<FONT COLOR="red">op1[O,S]</FONT>>,fontname=helvetica];
	}
    


    s->a [label="time", dir=back];
    s->p [label="op1"];
}
