This parameter defaults to the AIXM v5.1 XML Namespace URI http://www.aixm.aero/schema/5.1/message. This allows the writer to be configured to the AIXM v5.1 schemas without explicitly requiring you to set the .xsd file location with the Application Schema parameter.
Setting this parameter to Other allows you to alternatively provide the AIXM schema file via the Application Schema parameter.
The AIXM5 writer will parse the AIXM schema and write out features according to the feature types found in the schema. No other feature types, except the ones specified in the schema, will be written. The writer feature type definitions must then match the ones from the schema.
Importing the feature type definitions from the AIXM5 reader with the same settings will bring in the valid writer feature type definitions accepted by the writer.
Note: When importing feature type definitions to the writer the AIXM5 reader, you can leave the dataset unset.