Describes the WMO Core Metadata Profile. The primary purpose for this metadata profile is to support the DISCOVERY of information resources (datasets) WMO_DelimitedString enables a keyword from a hierarchical taxonomy - such as NASA's GCMD Science Keywords [http://gcmd.nasa.gov/Resources/valids//gcmd_parameters.html] - to be expressed. The delimiter (token) [default value = "|"] is inserted between 'levels' in the hierarchy. Allows differentiation between datasets from numerical simulations based on the analysis time of each simulation. This extension enables one to specify the time period during which the dataset is valid. Outside this time period, the dataset must not be used for operational purposes.