Effective dating: links that stop being true — What this does today

Dated links are stored, validated and policed on write, and resolution honours the period: a link whose period has ended is not returned, so lookups, rollups and computed fields that travel that relationship stop counting it automatically. What is not here yet is reporting as of a chosen past date — asking the workspace to show the world as it stood last March. The resolver already takes a date; nothing in the interface asks you for one. Today's behaviour is "as of now", correctly.