The Statistical Data and Metadata Exchange (SDMX) initiative is sponsored by seven institutions (the BIS, the ECB, Eurostat, the IMF, the OECD, the UN and the World Bank) in order to provide standards for the exchange of statistical information.

This standard describes and universalizes the way to exchange statistical data, and provides standard formats for data and metadata, content guidelines as well as IT architecture for exchange of data and metadata.

The SDMX message formats have two basic expressions, SDMX-ML (using XML syntax) and SDMX-EDI (using EDIFACT syntax and based on the GESMES/TS statistical message). This web service uses the SDMX-ML expression

Below are some terms that are used in SDMX and their definitions.

  • Dataset: a collection of related observations, organized according to a predefined structure

  • Data Structure Definition (DSD): metadata describing the structure and organization of a dataset, the statistical concepts and attached to them code lists used within the dataset.

  • Dimensions: concepts that determine the dataset's "physical" structure.

  • Code lists: A code list is a predefined list from which some statistical coded concepts take their values. Each code list has the following properties: a) identifier (it provides a unique identification within the set of code lists specified by a structural definitions maintenance agency); b) name (also unique); c) description (a description of the purpose of the code list); and d) code value length (either an exact or a maximum number of characters and a type, i.e. numeric or alphanumeric).

  • Attributes: give additional information about the concepts used and do not affect the dataset structure itself.

  • Dataflow: A structure which describes categorizes and constrains the allowable content of a dataset that providers will supply for different reference periods.
  • Concept Schemes: The descriptive information for an arrangement or division of concepts into groups based on characteristics, which the objects have in common. A concept scheme is a maintained list of concepts that are used in key family and metadata structure definitions.

(Definitions from EUROSTAT SDMX info space and OECD Glossary of statistical terms)

On March 16, a new version of the SDMX web services will be made available.
This will impact  the operations GetStructureSpecificData for SOAP SDMX 2.1 and data for REST SDMX 2.1
Further  information is available on SOAP SDMX 2.1 and REST SDMX 2.1