New icon in assembly tree

I am new to SW2009, and I have just completed a small fixturedesign for my Technologe noticed that there is a small icon thatlooks like a small dark rectangle beside each component in thedesign tree. I have looked through the whats new documentation andI have not found any helpful information.

I have attached a screen shot for clarity.

Can someone please help.

SolidworksAssemblies