Metadata: metadata is information about individual data sets which may describe, for example, how, when, and by whom data was collected/created; its accuracy, resolution and reliability with respect to some defined standard; how it may have been modified or analysed within a given context (e.g. data collected annually may be used to derive ten-year averages), and how it is formatted (e.g. for geographic data, projection and scale). The inclusion of metadata may be seen as analogous to a product health and safety warning in guiding users as to appropriate and inappropriate uses of the data set to which it applies.