Validation tools: can they indicate the information content of macromolecular crystal structures?

The explosive increase in the number of published three-dimensionsal structures of macromolecules determined by X-ray analysis places a responsibility on experimentalists, referees and curators of databases to ensure correspondence between the structure parameters and data. Validation tools will evolve as more appropriate statistical techniques and new information, such as that from proteins analysed at atomic resolution, becomes available.