This is DDI-Codebook version 2.6 submitted for review 2022-07-01.

THIS IS A REVISION of 2.5.1 and is backward compatible with 2.5 (a valid instance of DDI-Codebook 2.5 will validate against version 2.6).

The current publication includes the schemas, field-level documentation publication in HTML, and change documentation. Additional documentation on the use of DDI-Codebook 2.6 are published as separate documents on the DDIAlliance.org product page for DDI-Codebook.

The continued development of DDI-Codebook reflects the work of the committees and individuals who developed DDI versions 1.0 - 2.5 as well as the collective ideas, needs, and work of the Expert Committee of the DDI Alliance.

We would like to thank the following member organizations which have supported the DDI Alliance in their development of DDI version 2.6:

University of Alberta, Canada
Australian Bureau of Statistics (ABS)
Australian Data Archive (ADA)
University of California, Berkeley -- Computer-Assisted Survey Methods Program and UCDATA, USA
Centre for Longitudinal Studies, Institute of Education University of London (Associate Member)
Centro De Investigaciones Sociologicas (CIS), Spain
Cornell University (CISER)
Danish Data Archive
Data Archiving and Networked Services (DANS), The Netherlands
DataVerse
Finnish Social Science Data Archive
German Socio-Economic Panel Study (SOEP)
GESIS - Leibniz Institute for the Social Sciences
University of Guelph, Canada
Institute for Qualitative Social Science (IQSS) at Harvard University
Institute for the Study of Labor (IZA), Germany
Institute for Social and Economic Research (ISER)
International Association of Social Science Information Service and Technology (IASSIST)
International Federation of Data Organizations (IFDO)
Inter-university Consortium for Political and Social Research (ICPSR), USA
Massachusetts Institute of Technology (MIT), USA
Metadata Technologies, NA
Minnesota Population Center (MPC), USA
Norwegian Social Science Data Service (NSD)
Open Data Foundation, USA
Princeton University, USA
Research Data Centre of the German Federal Employment Agency, Institute for Employment 
  Research (IAB)
Roper Center, USA
Stanford University, USA
Statistics New Zealand
Survey Research Operations, University of Michigan
Swedish Social Science Data Service (SSD)
Swiss Data Archive for the Social Sciences (SIDOS)
University of Toronto Scholars Portal
United Kingdom Data Archive
University of Washington, Center for Studies in Demography & Ecology (CSDE), USA
United States Bureau of Labor Statistics (Associate Member)
World Bank, Development Data Group (DECDG)

DDI 2.6 XML Schema is released under the terms of the Creative Commons BY 4.0 (International). Details see the file license.txt.