This part of IEC 60626 contains the definitions related to and the general requirements to be fulfilled by combined flexible materials for electrical insulation. This document does not include mica papers used as a primary component, which are covered by the IEC 60371 series, but insulation materials based on mica paper can be used as component of a combined flexible material. Materials which conform to this specification meet established levels of performance. However, the selection of material by a user for a specific application is based on the actual requirements necessary for adequate performance in that application and not based on this specification alone.