DDI-Codebook v2.1

XML Schema namespace (use in xsi:schemaLocation declaration if not using a local copy of the schema set): https://ddialliance.org/Specification/DDI-Codebook/2.1/XMLSchema/Version2-1.xsd

DDI Codebook was the first version of the DDI to be published (Version 1 was released in 2000). DDI 2.0 was released in 2003, with Version 2.1 following two years later. The canonical expression of DDI 1.* through 2.1 is a Document Type Definition (DTD), although XML Schema versions have been created. The DTD can be converted to a schema using XML software, but the DTD should be used as the authoritative source for instance creation and validation.

Added Coverage

• Added Category Level (catLevel)
• Added attributes catgry and level to Cateogry element (catgy)