To have a concept of clockwise, there needs to be a circle somewhere. The circle needs a center and a radius. The center needs two points, call them X and Y. Call the radius R. So somehow you need three values, X, Y and R.

+---+---+    +---+---+
| 1 | 2 |    | 1 | 4 |
+---+---+    +---+---+
| 4 | 3 |    | 2 | 3 |
+---+---+    +---+---+
[download]

No circles, or radii, but most people would recognise the first as being "numbered clockwise from top left" and the second as "numbered anit-clockwise from top left".

Likewise these two sets of points describe the same irregular polyon

my @clockwise = ( [0,3],[3,0],[5,2],[4,3],[3,2],[2,3],[3,4],[2,5] );
my @anticlockwise = ( [2,5],[3,4],[2,3],[3,2],[4,3],[5,2],[3,0],[0,3] 
+);
[download]

which given the limitations of the medium looks something like this.

 | /\
 |/ /
 |\ \/\
 | \  /
 |  \/
-+------
[download]