What are the „Mounted“ & „Not mounted“ reference designators used for?

What are the „Mounted“ & „Not mounted“ reference designators used for?

myProto gives the opportunity to order items that do not need to be mounted or soldered on your boards, for instance a battery or a male connector that needs to be put into female connector. A designator reference is required for this product and has to be transferred from the “mounted list” to the “not mounted list” (See picture below). Therefore, components marked as “Not Mounted” will be taken into account in the orders price calculations & be purchased myProto and they will be delivered to the client along with his PCB.