These types represent more of those types that are useful primarily to processing applications. The types are used to specify a valid name(s). You might use them when you are associating some other component with the element, such as a Java class or a security algorithm

<!ATTLIST DATA AUTHORIZED_USERS NMTOKENS #IMPLIED>
<DATA SECURITY="ON"
         AUTHORIZED_USERS = "IggieeB SelenaS GuntherB">
blah blah blah
</DATA>