Content labels are used in search projects as a way of grouping content sets for querying. A content label can refer to one or more content sets. So, for example:

Catalog content label --> Products content set
Articles content label --> Brochures content set, Manuals content set

Each content label must be unique to a single set of linked projects. Two independent projects cannot use the same content label (though they can use the same content and have different content labels to refer to it), because content labels are used to differentiate independent projects for querying.

Linked projects, on the other hand, must share content labels. Linked projects differ only in the target type (Production, Staging, etc.). Each target type must be unique to one project within a set of linked projects. Two linked projects cannot use the same target type, because the target type is used to determine which search environment within a set of linked projects to direct queries to.

To specify the content labels and target type for a query, you set the contentLabels and targetType properties on the QueryRequest component in a properties file or JSP. For example:

contentLabels=Catalog,Articles
targetType=Staging

By default, the /atg/commerce/search/catalog/QueryRequest component has the following configuration:

contentLabels=Catalog
targetType=Production