Polar Grid Display (747-400)
 

Chaps...
I'm aware of a feature on the 747-400 known as the (Polar) Grid display. Until recently, I had never seen this display in real life(never having been in polar regions). I was working (in an engineering capacity) on a Korean Airlines' aircraft last week and noticed that the Grid display (box and dashes only) appeared on the ND during IRS alignment, but disappeared when the IRS's entered Nav Mode.

Is this brief appearance during IRS alignment a good indication that the Grid display _option_ is active on a 400, or is it just a KAL quirk?

Thanks.
Rgds.
Q.