SDMX Metadataflow Structure Module The metadata flow structure module defines the structure of metadata flow constructs. MetadataflowBaseType is an abstract base type that serves as the basis for the MetadataflowType. It restricts the structure to reference a metadata structure definition. Structure provides a reference to the metadata structure definition describing the structure of all reference metadata for this flow. MetadataflowType describes the structure of a metadata flow. A dataflow is defined as the structure of reference metadata that will be provided for different reference periods. If this type is not referenced externally, then a reference to a metadata structure definition must be provided References identifiable structures to which the refernece metadata described by the referenced metadata structure should be restricted to. These references may include wildcards for parts of the reference.