http://www.movielabs.org/creativeworks/model/eidr#originalTitleIsRequired
Property 'original title is required'

DatatypeProperty

Series or Season

original title is required

boolean

If true then all children (Seasons or seasonless Episodes of a Series, Episodes of a Season) must specify a self-defined title. Most modern fictional series episodes will have one, while seasons almost always do not. This is usually not present or false at the Series level.