How does zoho create doc files on the fly?

How does zoho create doc files on the fly?

Hello all!!

I need a writer for an application of mine but I cannot make it neither read nor save the contents as a doc file. I have been googling and searching many places but still couldn't find how to save WYSIWYG contents as a .doc file, so any help would be greatly appreciated.

Thank you all for your time and cooperation.