 This period also saw the splitting of the ICD into dedicated Part 1 (interface requirements) and Part 2 (physical and functional definition) at Revision D (June 1996).By the time a final framework for the international effort was contractually established in December of 1996, the first CBM simulators had already been delivered to NASA.Having been specified independently, compliance for most requirements of the ACBM and PCBM was verified separately.