Indictio (The Indiction)
Lat. indictio ('proclamation of assessment') < indicere ('to declare')
A 15-year recurring fiscal calendar cycle originally instituted by Emperor Constantine the Great in A.D. 312, universally adopted by early Christian chanceries to date documents alongside the calendar year.
Because indiction numbers cycle from 1 to 15, comparing the recorded indiction against the recorded Year of the Incarnation provides modern diplomatic scholars with an infallible check on the authenticity of a diploma.
Invocatio (Pious Invocation)
Lat. invocatio < invocare ('to call upon, invoke')
The solemn initial clause of an Anglo-Saxon diploma invoking the Holy Trinity, Christ, or the Divine Majesty to sanction the legal act and place it under heavenly protection.
Early Insular invocations often feature the Chrismon symbol (+) or phrases like 'In nomine Domini nostri Iesu Christi'. In pre-900 Kentish and Mercian diplomas, invocations establish spiritual legitimacy before the secular royal dispositive verb.
Iugum (The Yoke)
Lat. iugum ('yoke of oxen') / OE geoc
A fractional land division in Kent equal to one-fourth of a *sulung* (or half of a standard hide), measuring approximately 50 to 60 acres.
Frequently granted in Kentish charters for small pasture allotments, salt-pans, or swine-pasture woodlots in the Weald.