Freeform Annotation
I realized that aeva already has a feature that it inherits from smtk, which can be leveraged for freeform annotation.
smtk::session::SetProperty
This feature allows providing a user-defined name and value pairs for the annotation, e.g. AgeCategory and Elderly (see image below).
Maybe we can expose this feature more clearly as an aeva annotation operation, e.g.
smtk::session::FreeformAnnotation