If the same type of hairs exist on both the stem and the leaf, it is not sufficient to place hairs outside the group containing both stem and leaf. It is possible that characters and structures have overlapping hierarchies, that can not be resolved into a simple tree. For example, the same hairs may occur on many different structures, which can not be grouped hierarchically. A Ref-ID mechanism is necessary to document the relations between structures, substructures, and properties. Leaflet is a part of a leaf.
Features have qualifiers.
Certain conditions are called epitopic child birth is possible only in female, and only in female that is pregnant and of appropriate age. In some cases a character is implicitly only possible to observe using a certain methodology.