Machine-actionable study descriptions in DDI-Codebook 2.5 Format

FSD's machine-actionable study descriptions are now available in version 2.5 of the DDI-Codebook specification. Metadata files released earlier in DDI 2.0 have been replaced. DDI 2.5 metadata have already been available through our OAI-PMH interface.

With the introduction of DDI-Codebook 2.5, metadata interoperability has been improved. This version enables file validation using XSD schemas and offers wider possibilities in utilising persistent identifiers.

DDI Codebook (logo)

The conversion to DDI-Codebook 2.5 did not alter the content of study descriptions. The following technical changes have been implemented:

  • Removal of the DOCTYPE declaration
  • Change of the "codeBook" element to:
    <codeBook xmlns:xsi="" xmlns="ddi:codebook:2_5" version="2.5" xsi:schemaLocation="ddi:codebook:2_5" xml:lang="ISO 639-1 language code">