SCE — Refences to non-existing specifications

For context, SCE contains references to KPMN & PPMN as standards that had planed to use SCE. However, the KPMN Finalization Task Force decided not to finish their specification and did not submit an FTF report. As a result, KPMN is not a viable specification for SCE to reference. PPMN has yet to be finalized and although its Finalization Task Force is active, it is not far enough along to be sure that it will pass all checks & votes in time and be adopted.