To produce a version of INAP for CS2 with as few options as possible suitable for implementation in Europe. Close co-operation must be ensured with SPS2 with regard to CTM and UPT support. Other aspects which need to be addressed are those surrounding VPN such as CTN and GVNS. The Call Party Handling procedures must also be supported. The validated SDLl model must be part of th enormative text and shall define the behaviour of the various operations applicable for the defined IN CS2 functional interface. The specification should also address aspects of interaction between IN structured networks. As a result of this, new IN functionality may be identified such as the interworking function; the impact this has on the INAP and ISUP/DSS1 will need to be explored. The CS2 definitions should be fully compatible with the existing CS1 INAP.