Organize collection dialog. Unavailable parts replacement

[Sergey Ivanov]

Hey, guys. How do you think, what would be better: replace unavailable
tags with some string-substituter like "NA", or just skip It? Below is
example, to make clear what exactly I'm talking about.
We're using collectionDir/%artist/%disc/%discnumber/%title.filetype
scheme to organize collection files. But some of this tags/fields
unknown, %disc for example.
So we should move tracks to
"collectionDir/Artist_Name/NA/Disk_Number/" folder or to
"collectionDir/Artist_Name/Disk_Number/"?

-- 
Sergey Ivanov