how to create a filename suffix [closed]

[gludgeunliz]

I want to create a new suffix for a particular file system.Instead of using;\[code\]yourname.doc\[/code\]\[code\]yourname.txt\[/code\] \[code\]yourname.pdf\[/code\]I would like to create \[code\]***yourname.med***\[/code\] as a suffix. Does anyone have any suggestions?