Combining tags to display as one, by aliasing?

[marcaurel]

Could you please describe the steps to make a COMMENT tag visible under "Desc." in "Show Metadata" of BubbleUPnp.
I took an album, wrote a COMMENT tag to the first song, added "Comment" to itemTags in minimserver Properties and rescanned.
But still no desc. in " Show Metadata" when I play the tagged song.

What have i done wrong?
What tags can be made visible in "Show Metadata" in addition to the standard tags like Title, Album, Artist, Composer, Year and Genre?