  It is widely recognized that the proliferation of annotation schemes runs
counter to the need to re-use language resources, and that standards for
linguistic annotation are becoming increasingly mandatory. To answer this need,
we have developed a framework comprised of an abstract model for a variety of
different annotation types (e.g., morpho-syntactic tagging, syntactic
annotation, co-reference annotation, etc.), which can be instantiated in
different ways depending on the annotator's approach and goals. In this paper
we provide an overview of the framework, demonstrate its applicability to
syntactic annotation, and show how it can contribute to comparative evaluation
of parser output and diverse syntactic annotation schemes.
