Does it really matter? Skin crease, centred over the little blue line (superficial epigastric)
See Scarpa’s, open Scarpa’s, then look for the fibres of external oblique. Move the retractors up and down to see if there’s one more fine layer to go through. Then…
You have to see the border of external oblique, where it rolls under to form the inguinal ligament. Then…
Follow the line of the inguinal ligament. See where the cord exits and the angle changes. Look for the intercrural fibres. If in doubt, in boys pull on the testis and see the cord tighten. Only then can you open the canal or start dissecting the cord.