gEDA-user: GAttrib refdes appends '.'

[Dan Sandberg]

Why does gattrib show some components with a dot ( period ) appended to 
their refdes?

IE, it lists the components like
U1,field1,field2,field3
U2.,field1,field2,field3
U3.,field1,field2,field3
U4,field1,field2,field3

I could find anything in the manual about what the '.' symbolizes. 

Thanks,

-Dan