Color fill indication explanation

Hello,

I'm kinda new to the CorelDraw and i would like to know what those symbols on color fill means (picture below), i couldn't find it anywhere. I checked CorelDraw X6 handbook, Help and of course Google. So this place looks like my last chance to unveil this mystery.

Some info: This symbol on color fill icon exlusively occurs when i import vector graphics that wasn't created by me. Sometimes it cause the are with fill isn't printed.

 

Many thanks for any responses in advance.

Corel user Jan.