An Xper3 reference guide for taxonomists: a collaborative system for identification keys and descriptive data

The Xper3 software enables collaborative management of descriptive data on taxa. This paper focuses on the essential information about the knowledge model that underlies the software, its features and user interface which has been evolving since 2014. The best practices for representing taxonomic descriptions, managing polymorphism and missing data in a consistent way are also presented. Its ease of use and the versatility of its data model mean that the software can be used to create and distribute identification keys for all types of taxa