The development of an abstract model for a taxonomic concept, which can capture the various models represented and understood by the various data providers, is central to this project. This model is presented as an XML schema document that is proposed as a standard to allow exchange of data between different data models. It aims to capture data as understood by the data owners without distortion, and facilitate the query of different data resources according to the common schema model. The TCS schema was conceived to allow the representation of taxonomic concepts as defined in published taxonomic classifications, revisions and databases. As such, it specifies the structure for XML documents to be used for the transfer of defined concepts. Valid transfer documents may either explicitly detail the defining components of taxon concepts, transfer GUIDs referring to defined taxon concepts (if and when these are available) or a mixture of the two.