Playing MP3 Files

With some audio files, the UltraPlayer Status Display shows the kbps as "--". What does this mean?
When UltraPlayer plays a file that was not encoded at a Constant Bit Rate (CBR), "--" is displayed in the "kbps" field. The "kilobits per second" rating only applies to files that are created using a constant compression format. WAV files, CD Audio tracks, Video Files and Variable Bit Rate (VBR) files are not created this way, therefore UltraPlayer displays "--" in the "kbps" when playing them.