PDM Workgroup Icon question

When I click expand the + of one of the assly in my PDMworkgroup, I see that few icons of the parts & drawings shown like a shortcut key (Like in windows shortcut icon with a small arrow)
At the same time few parts & drawings are not having the shortcut icon symbol.

I need to know what the difference is? benefits?

Anybody noticed this?
SolidworksWorkgroup Pdm