The Expert Team on Metadata Standards (ET-Metadata) develops and maintains WMO metadata standards for discovery, observations, provenance, WIS2 notifications, topic hierarchies, and monitoring, aligned with W3C, OGC, and ISO/TC 211 standards. It documents standards in key WMO manuals (WMO 1060, 1061, 306, 1192), develops quality assessment frameworks, harmonizes requirements with international standards bodies, evaluates metadata profiles and tools, provides recommendations for future evolution, and maintains codes.wmo.int while preparing best practices and implementation guidelines.