This specification provides a definition of AliasNames functionality. AliasNames provide a manner of configuring and exposing an alternate well-defined name for any Node in the system. This is analogous to the way domain names are used as an alias to IP addresses in IP networks. Like a DNS Server, an OPC UA Server that supports AliasNames provides a lookup Method that will translate an AliasName to a NodeId of the related Node on a Server. An aggregating Server can collect these AliasNames from multiple Servers and provide a lookup Method to allow Client applications to discover NodeIds on a system wide basis. An aggregating Server might also define AliasNames for Nodes in other Servers that do not support AliasNames. A GDS may be constructed that would automatically aggregate all AliasNames that are defined on any Server that has registered with the GDS. In this case the GDS also provides the lookup mechanism for Clients at a well-known endpoint and address. The GDS functionality for AliasNames is formally defined in Annex B.