string rule = "\hbox to 30pt{\vrule height 10pt depth 2pt\hrulefill\vrule height 10pt depth 2pt}";
unitsize(20mm);
dotfactor = 4;
labelmargin = 0.5;

label(rule, (0,0));
dot((0,0), red);
label("nic", (0,-0.5));

label(rule, (1,0), N);
dot((1,0), red);
label("N", (1,-0.5));

label(rule, (2,0), 2N);
dot((2,0), red);
label("2N", (2,-0.5));

label(rule, (3,0), W);
dot((3,0), red);
label("W", (3,-0.5));

label(rule, (4,0), S);
dot((4,0), red);
label("S", (4,-0.5));

label(rule, (5,0), dir(30));
dot((5,0), red);
label("dir(30)", (5,-0.5));