Perhaps “excise” is not quite the right term here (esp since it has a meaning within normal tid editing). Anyway, idea is that if a tid exists named “New field”, and recognised as a field definition tid via it’s own “field-type” field (and perhaps others?), then just the bits that define it as a field definition tid could be elevated out to “▭ New field” style - the new one having the fields that are relevant to it being a field definition tid copied over, and the normal tid fields remaining with the original. (Whether the field-type (and others) fields are removed from the original, or remain (but ignored because of the precedence of the new field definition tid), is a matter of lesser importance. I’d be inclined to leave them be, and those fields within the ‘New Field’ tid effectively become “shadow field definitions” - they exist but are unused.

although not compelling on its own. I think in the fullness of time examples that are compelling may be found
That’s my feeling on the matter too. Tid’s being able to define fields to multiple other tids via field definitions, feels like it’ll enrich the interconnectedness and organisational possibilities of TW.