DDI, short for Data Documentation Initiative, is an international metadata standard for data documentation. The DDI specification, currently written in XML, provides a format for content, exchange, and preservation of information. It enables documenting data collection, surveys, and statistical data files in a common XML format.
This repository publishes changes to the DDI Lifecycle schema over time. It includes all release candidates, public reviews, and official releases. It currently covers DDI version 3.0, 3.1, and 3.2.