A closed wound is one where skin is intact and underlying tissue is not exposed to the environment.
Abrasion is an erosion of skin usually due to sheering force. In most cases the dermis is intact and the injury is superficial limited to epidermis. Abrasions heal without scarring by epithelialization.
Are abrasions considered closed wounds? I would think they are open wounds as the underlying tissue (which would be dermis in this case) are exposed to the environment. Please state the reason why they are classified into whatever group.