A method for updating data to ensure the correct version of the data is available for a user of a second data system. In the second data system, an update request is received from a first data entity to update the data in a component of the second data system. The update request comprises an updated version of the data. The updated version of the data is compared with a currently stored version of the data in the second component to determine a change therein. An operating function representative of the change in the data is produced. The operating function is applied to the currently stored version of the standard data to produce resulting data. The operating function is stored to ensure the correct version of the data is capable of being output if requested.