The controlled lists help implement the e-Government Metadata Standard (eGMS) by providing standard vocabularies to use when describing resources, such as Web pages.
The GovTalk Web site describes eGMS at: http://www.govtalk.gov.uk/schemasstandards/metadata.asp
Specific guidance from the LAWs and CRM National Projects is given at: www.esd.org.uk/standards/egms. These Web pages include an interactive viewer of eGMS elements. They indicate where each controlled list is appropriate to populate metadata elements.