Pitney Bowes MapXtreme - Manual (Page 595)

Appendix I: User-Defined Metadata
User-Defined Metadata Support for TableInfoServer Queries
MapXtreme v7.1 602 Developer Guide
In this example, the StringCollection class resides in the System.Collections.Specialized
namespace.
Composite keys are allowable and would be defined by adding two or more column names into the
string collection.
Explicit key definitions may also be used as overriding definitions in cases where the database table
contains two or more candidates, and the developer has a specific preference for which gets used.
Workspace Persistence
User-defined metadata constructs for column hints and key definitions are persisted as part of the
data source definition tag within a workspace file (.mws).