Relationships are async clock interfaces
A relation between any two individuals is an asynchronous clock domain interface with two different clocks on either side. Very rarely the interface is synchronous. The power domains, voltages, signoff corners can be different. Each following a different protocol. To make it work still, a suitable synchroniser logic needs to be built as a bridge with sufficient depth. One may be running at high voltage at some point but Level shifters need to be added to get along. One may be down, power gated sometimes and isolation cells may be needed with appropriate controls. Retention helps to maintain the relationship. The interfacing logic still need to be placed closer with max delay constraints and skew and latency requirements so they listen to each other still. The setup has a cushion but hold with a lot of patience need to be closed at cross corners covering the extremes. Temperatures may rise and cold wars may arise but hold needs to be closed to maintain the functionality. It should...