With the growing complexity and quantity of biosimulation models, annotation tools that can accommodate a variety of modeling languages and simulation environments were needed to encourage models which could be easily understood and uniquely identified. The COMBINE community developed a consensus on the utilities required for this open-source, cross-platform software library for model annotation.

libOmexMeta is a C++ library, developed by Ciaran Welsh, which has an associated Python front end, pyomexmeta. Together, libOmexMeta and pyomexmeta enable semantic annotation, which connects model elements to standardized vocabulary terms, and ideally encourages users to add biological ontology terms and standardized identifiers to describe the components of the model. libOmexMeta uses the Resource Description Framework (RDF) to represent the annotations in a structured format that can be stored independently of model descriptions.