If a geophysical survey is split into smaller data grids (see above) their corresponding data files have to be re-assembled into an overall data entity. To achieve this a ‘mesh’ is used that indicates the relative position of each data grid in the overall survey area. It is hence a map of the data grid layout but does not contain measurement data itself. It often takes the form of a spreadsheet table and is also referred to as ‘master grid’ (Geoplot). Using this mesh the data grids are assembled to form a ‘composite’ for the whole survey area. This will also take the form of a gridded data structure with associated metadata but for a much larger area and allows data processing irrespective of the arbitrary data grid boundaries that were introduced during the survey.