How to store back a translated file in .xlf format

Hallo,

I am using SDL Studio 2015 SR2. 

I need to translate an .xlf format file. SDL Studio is able to read in the .xlf file correctly and the translation also proceeds well.

However, I can only store back the translated file as .xliff file and not as .xlf file.

Question: How can I store back the translated file as .xlf file please?

Ans suggestion or tip would be most welcome.

Thanks and best regards

Shyam Gupta