http://blogs.msdn.com/brian_jones/archive/2005/06/01/424085.aspx
I think there are 2 points here that may affect us.
- Probably the coolest – word documents, xl spreadsheets and even powerpoint files will be stored as XML with the format being fully documented. There will be updates to Office 2000, XP, and 2003 so they can use these new formats. I can see being able to dynamically create Word docs, spreadsheets and powerpoint presentations on the fly (for reports, etc) much easier than we’ve been able to in the past. I have created dynamic Word document reports in the past, but it involved a scripting tool that actually created RTF files and then served them up with a .doc extension. Because the file had a .doc extension, the browser used Word to open the file and being an RTF file, Word knew what to do with it. It worked, but not nearly as elegant as the future could bring. I imagine there will initially be a rush of components built that will perform this file-building, and then eventually it may even be built into the .NET Framework or offered by Microsoft as developer extensions for Office. That would be nice.
- There will be new file extensions for the new XML format: .docx, .pptx, and .xlsx. I can think of half a dozen applications that I have built in the past that check the file extension to determine if the user is allowed to upload the file. Of course none of them check for these new extensions, so the user would not be allowed to upload files with these new file formats. The post mentioned that the binary formats will still be supported, but I assume the new formats will be the default. So we could have a usability issue created. Of course users could go back and re-save the file into the older format and then upload it, but that is kind of a pain in the butt and exactly the kind of thing we usually try to avoid. I’ll keep an eye out for sites that I know of that do this file extension checking and make note of them – one of them is the site that I am working on now.