As a survey progresses, changes are sometimes made to the questionnaire. For example, questions and categories might be added and deleted. Typically a new version is created in the metadata each time a change is made to the questionnaire and each version corresponds to a variation of the questionnaire used for some of the interviews.

When you load a data set that contains more than one version, all of the versions are combined to form a superset (sometimes called a superversion). This means that all of the variables and categories from all of the versions are available. When there is a conflict between, for example, a text in one or more of the versions, the more recent versions generally take precedence over the older versions. However the order of questions and categories is always taken from the most recent version.

Case data collected using UNICOM Intelligence Interviewer - Server Admin has the name of the version used to collect it stored in a system variable called DataCollection.MetadataVersionNumber. You can use this to filter case data based on the version used to collect it. Typically you would create the filter as a global filter, which means that it will be applied to all tables automatically.

In data collected using tools other than UNICOM Intelligence Interviewer - Server Admin, the DataCollection.MetadataVersionNumber system variable might not store the name of the version, depending on how the data was set up.