consider adding a concept node

[matt-beanland]

we missed having a concept node rooted to the standard, but the concepts while used in the standard are universal, so the concept root is elsewhere and not shown.

[matt-beanland]

In all likelihood they won't root to concept, but the concepts will root to a field. In some cases we've tried to explain a term such as transition in relation to concepts.
The standard used transition, which we rooted from the standard but labelled concept. We then enumerate two more concepts arriving and leaving, which both relate to rising and falling edge the same way. We could improve that.

indeed clock, sample, domain and synchronicity were my additions from digital logic.