Contact placement is derived from the OD dimensions and enclosure rules. The SKILL code computes safe Y-ranges to ensure DRC compliance.
(contRowYclear (- (/ odWid 2.0) contEncOD))
(contYmin (- contRowYclear contSize))
(contYmax contRowYclear)
Metal-1 straps are then extended beyond the contact rows to guarantee sufficient enclosure.