This code repository contains the "back-end" of the Nexus Microscopy Facility Laboratory Information Management System (NexusLIMS), developed by the NIST Office of Data and Informatics. Its primary function is to build XML-formatted research experiment records by combining metadata from many different sources (reservation systems, the collected data files, a session logger, etc.). These records are structured according to the "Nexus Experiment" schema, meaning they can be loaded into a repository and used for structured data queries.