BTW. Your image is correct if the line represents the actual thickness of the line laid down by the designer or if no physical line, the thickness of the object that is the Mandatory. If the Mando object thickness is that of your dot, your drawing is incorrect.
A couple of points--they are using the term plane, so that's two dimensional. Krupicka said earlier the mando orientation should be marked by the TD, which is likely to be string.
By default, since I drew the line on the example, that IS the thickness of the mando in the example, i.e., it was intentional.
With regard to route options based on where the disc lies and how it gets to it's lie, BillFleming has further clarified the question we are trying to resolve.