The position mark is required when the sign alone can’t be registered as a trademark. The German doctrine gave birth to this notion to protect this kind of sign as mark. Hence, if the sign by itself is capable of being protected, the position mark is not needed (for example the sign “coca cola” don’t need a special positioning for being protected) and the application as a position mark makes sense when it is the only way to reach the protection of the sign.
To resume the German understanding of the position mark, it is a sign, positioned on a special part of the product in a constant size or in a special proportion to the product (for example: in a relative distance to the middle of the product) or silhouetted against the product (for example in a special contrast).