This files describes API changes in /dataformat/ download system, information provided here is intended especially for developers. === 3.4 === * In order to allow multiple sheets in an exported file the functions write_header() and write_footer() have been removed from core dataformat plugins and have been replaced. - write_header() has been replaced with the two functions start_output() and start_sheet(). - write_footer() has been replaced with the two functions close_output() and close_sheet(). For backwards compatibility write_header() and write_footer() will continue to work but if used will trigger the function error_log(). === 3.1 === * Added new plugin system with low memory support for csv, ods, xls and json