This document proposes a detailed system called CostumeCore for digitally cataloging historic clothing based on existing standards. It summarizes existing metadata schemas, controlled vocabularies, and guidelines that provide the foundation for CostumeCore. Specific elements are added to describe costume objects, and a visual workflow is presented to help catalogers choose terms from controlled lists. The system is intended to standardize digital costume catalogs while allowing customization for specific collections. Feedback is sought from others to improve the system.