A questionnaire can undergo many changes, both before data collection begins and during the course of a survey, which may run for an extended period of time. A version of the metadata can be considered a snapshot of the metadata that was used to collect case data. You create a new version of the metadata whenever you activate a questionnaire.

The UNICOM Intelligence Data Model allows you to track the version history of the metadata by storing all versions of the metadata alongside one another. When you collect data using one of the UNICOM Intelligence products, each case in the case data can be flagged with a version number so that you can always determine the exact questionnaire that was used to gather the data. This avoids the confusion that can result when several very similar copies of the metadata are in use at once. All versioning information is stored in a single location. To view the texts and routing instructions from a given version of a project, you simply set the desired version as current and the MDM Document reconstructs it for you, presenting only the metadata associated with that version.