Namespaces are used to demarcate vocabularies. If two terms each belonging to a different namespace have the same spelling, then the terms are treated as different and non-conflicting.

A namespace is identified by a URI (Unique Resource Identifier). Usually, a short prefix is associated with the namespace. This prefix can be used to qualify the terms, so it is apparent to which namespace they belong.

In MAJAS, namespaces are used to group feature types together, and associate them with a set of data stores. In the example above, the "postgis" namespace is defined, and associated with the "PgTestDS". More than one data store can be associated with a namespace (but not vice versa).