SeriesKey

Cross product of values of dimensions, where either the cross product or the cross product combined with a time value, identifies uniquely an observation.

Most series keys are combined with a time value in a data set in order to identify uniquely an observation. There may be particular series keys that do not require a time value in order to achieve this, so the “Time Dimension” is not obligatory in an SDMX Data Structure Definition. In an SDMX data set there must be a value for all of the Dimensions specified in the Data Structure Definition when reporting data for a series key.

The combination of the semantic of the names of the concepts used by the Dimension (excluding time) describes a series key. Unless the Data Structure Definition contains multiple measures this semantic is often the semantic of the observation.