thanks for the answer. 

I am referring to this : 

http://msdn.microsoft.com/en-us/library/ee372313.aspx

As fas as I understand, each content type can only be export for one, or more file extensions statically at compile time. 

How do I export content types dynamically based on some user options for example? Is this not possible purely by MEF?

Thanks!

I am trying to implement syntax highlighting, intellisense etc. for a specialized language and I was hoping to use MEF. However since this heavily relies on providing a file extension at compile time and one requirement is that this extensions should apply to many different file extensions.. E.g. .atm, .bar, .foo .. 

There seems to be no documentation whatsoever on the net. The only success I had was by reverese engineering IronPython tools.. 

Thanks for any pointers..