The GDS may include additional optional behaviour which this example illustrates. What is required is the availability of all AliasNames in the mandatory TagVariables and Topics folder, but a GDS may also choose to replicate or even merge the additional AliasNameCategoryType instances from the Servers that have registered. Figure A-7 provides an illustration of a GDS that merged the AliasNameCategory instance into a tree. It is required that AliasNameCategories be aggregated by the GDS, but the structure of these categories is not defined.

Figure A-7 - GDS with merged AliasNames example

For additional information about a GDS and AliasNames see Annex B.