The mysterious symbol

I've been trying to fetch some informations about this alien rune that appears sometimes on the side of sample names:


Needles to say that the manual don't tell a single information about that.
After using the AKAI S900 for years I still havent figured out when it comes out and WHAT DOES IT MEAN.

In fact the mysterious symbol is not always shown:


But sometimes it appears after sample name:

ANY CLUE??