Complex sentence: IBM designed IMS with Rockwell and Caterpillar starting in 1966 for the Apollo program, where is was used to inventory the very large bill of materials (BOM) for the Saturn V moon rocket and Apollo space vehicle.
Split into simpler sentences: IBM designed IMS with Rockwell and Caterpillar starting in 1966 for the Apollo program. IMS's challenge was to inventory the very large bill of materials (BOM) for the Saturn V moon rocket and Apollo space vehicle.