Any source format for micro-history data must be extensible in order to accommodate unforeseen circumstances or cultural variations.
There are three main types of extension considered here: Extensions to the schema itself to define new element types, extended properties for Person, Animal, Place, Group, or Event entities, and extended vocabularies for types, etc. The latter two are deliberately made easy since they will be more common. Extending the core schema is controversial, and not really recommended, but the possibility is included here for completeness.
Note that there is no real need to introduce other types of Person-to-Person linkage to supplement the existing ones that represent biological lineage and association via Role and Relationship through shared Events. The fact that Narrative text can reference any Person, Animal, Place, Group, or Event means that the data model already has a fundamental capability to link elements for arbitrary reasons. This, in turn, is necessary for it to be applicable to micro-history in general. Although the conclusional sub-model, in the form of Properties, describes relationships in terms of a normalised vocabulary, the informational sub-model, in the form of the Source entity, can describe any subject-to-subject relationship using the informal vocabulary of the user or the source.