The flashing detail placed over the top of an exposed wall at the roof or at horizontal interfaces between siding materials.  In the case of a wall cap it is usually composed of metal, used to cover or shield the top of the wall below and cover the top of the upper edges of the membrane, base flashing, wall flashing, or primary flashing.

When used at a horizontal interface between siding materials having a different depth it is the flashing detail that extends from behind the upper siding water resistant barrier over the lower protruding siding to direct water to the exterior of the siding envelope.

Coping flashing should alway be lapped by the water resistant barrier in a roof lap fashion at interfaces.  A lack of a proper interface, improper joints, or improper fastening are common defects.