Manipulation of features which refer to annotations and matching on simple features is currently supported, but matching on the complex values of some feature is not. A first step can be something like (Type Person with feature "title" of type Annotation):
This rule matches on all annotations, which are values of features of annotations of the type Person.
This new language element can also be used for syntactic sugar when checking primitive feature values:
Person.begin=0 (A Person annotation, which starts a offset 0)
This can only be a first step towards supporting tree structures. Maybe there is no way around something for explicitly and directly referring to certain annotations (which is not possible right now, but is done by using the type).