PHPExcel set specific headers for file format - php

Question

While googling I found two different sets of headers that need to be set when outputting excel generated in different file format.
for e.g.
For Type "Excel5" headers are:
header("Pragma: public");
header("Expires: 0");
header("Cache-Control: must-revalidate, post-check=0, pre-check=0");
header("Content-Type: application/force-download");
header("Content-Type: application/octet-stream");
header("Content-Type: application/download");;
header("Content-Disposition: attachment;filename=$filename");
header("Content-Transfer-Encoding: binary ");
For Type "Excel2007" headers are:
header('Content-Type: application/vnd.openxmlformats-officedocument.spreadsheetml.sheet');
header('Content-Disposition: attachment;filename="myfile.xlsx"');
header('Cache-Control: max-age=0');
My question: is there need to set up different headers for each file type as there are other file types also CSV, HTML and PDF?

Answer 1

header("Pragma: public");
No - this is just wrong - though lots of people think it has something to do with caching
header("Expires: 0");
header("Cache-Control: must-revalidate, post-check=0, pre-check=0");
Nothing to do with Excel - these just control caching
header("Content-Type: application/force-download");
header("Content-Type: application/octet-stream");
header("Content-Type: application/download");;
No - there should only be one content-type header. For a MS Excel file using OLE, the mimetype should be application/vnd.ms-excel
Only the second header above is a valid mime type.
header("Content-Disposition: attachment;filename=$filename");
header("Content-Transfer-Encoding: binary ");
The second header is redundant, the former specifies a filename for the download.
Content-Type: application/vnd.openxmlformats-officedocument.spreadsheetml.sheet');
Only for a .xlsx file (i.e. saved in XML). Otherwise you should use application/vnd.ms-excel. Indeed the latter should be backwardly compatible.
My question: is there need to set up different headers for each file type
Yes - the Content-Type header is the file type. But only this header needs to change.
C.