Definition of information that is recorded against time, such as information monitored during the run. It contains the logged values and the times at which they were measured as elapsed time since a starting time recorded in ISO8601 format. This method of storing logged data helps to distinguish instances in which a variable is a dimension scale of the data, in which case it is stored in an NXdata group, and instances in which it is logged during the run, when it should be stored in an NXlog group. Note: When using multiple NXlog groups, it is suggested to place them inside a NXcollection group. In such cases, when NXlog is used in another class, NXcollection/NXlog is then constructed. Time of logged entry. The times are relative to the "start" attribute and in the units specified in the "units" attribute. Array of logged value, such as temperature Array of raw information, such as thermocouple voltage Description of logged value estimated uncertainty (often used: standard deviation) of average_value Total time log was taken