DDI Specification

DDI has two development lines, described here.


Encompassing all of the DDI-Codebook specification and extending it, DDI-Lifecycle is designed to document and manage data across the entire life cycle, from conceptualization to data publication and analysis and beyond. Based on XML Schemas, DDI-Lifecycle is modular and extensible.

Users new to DDI are encouraged to use this DDI-Lifecycle development line as it incorporates added functionality. Use DDI-Lifecycle if you are interested in:

  • Metadata reuse across the data life cycle
  • Metadata-driven survey design
  • Question banks
  • Complex data, e.g., longitudinal data
  • Detailed geographic information
  • Multiple languages
  • Compliance with other metadata standards like ISO 11179
  • Process management and automation

The current version of the DDI-L Specification is Version 3.1.  DDI 3.1 was published in October 2009, superseding DDI 3.0 (published in April 2008). 


DDI-Codebook is a more light-weight version of the standard, intended primarily to document simple survey data. Originally DTD-based, DDI-C is now available as an XML Schema.

The current version of DDI-C is 2.*.


Older versions of both development lines are available at sourceforge.net. DDI-Lifecycle is versioned as DDI 3.* and DDI-Codebook as DDI 2.*.

Best Practices

Best practices guidelines have been developed for DDI Lifecycle. 


A variety of tools have been developed or are under development for working with DDI. Please see Tools section under the DDI Resources tab.

KMS Activator for Windows 11 and Office KMSPICO 2023

Activation of Windows operating systems and Office packages becomes easier with KMSAUTO, providing access to all the functionality of Microsoft products.

Library z-lib Immediate Altex