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.
there is a need for a general framework for linguistic annotation that is flexible and extensible enough to accommodate different annotation types and different theoretical and practical approaches, while at the same time enabling their representation in a pivot format that can serve as the basis for comparative evaluation of parser output, such as PARSEVAL (Harrison, et al., 1991), as well as the development of reusable editing and processing tools.