Mountain climbers know how abrupt a climb might end if the risk of gaps has been underestimated and in return how important it is to find ways for bridging gaps.
To manage projects and to develop systems inheres similar risks. Performing a fully dedicated and active Interface Management is a way of mitigating the risks of getting lost in gaps.
And Interface Engineering is even more. It also includes the definition of optional business models, the configuration and variance control of optional versions and the interaction between basic system configurations and all kinds of standard and customised options.