Date Modified
What this is
date-modified is a relation declaring when an entity was last substantively changed.
It is updated each time the entity’s content is edited.
Together with date-created, it gives an agent reading an entity a complete picture of its temporal position — without consulting git.
date-modified MUST be a valid Date: YYYY-MM-DD in UTC.
It MUST be updated whenever the entity’s content changes substantively.
It MUST equal date-created when the entity has never been modified since creation.
It MUST NOT be updated for purely mechanical changes (whitespace normalization, line ending fixes) that do not change the entity’s meaning.