where you can buy the downloads by quadrant. i bought several of these years back ( proir to gps ) for back-packing. as for if that was the name of a quardant i could not tell you. i am sure each government has a different way to name their maps
It should be Pl.Qu., or Planquadrat (German for grid square). 06 Ost is the square containing Norway.
Much information can be found on SES' website, here: Reporting grids. The downloadable LUMA convertor on that page will provide an exact location for your Pl.Qu. reference.
Not sure what the problem is there, but I entered the figures into my LUMA convertor, and it came up with 61 22 30 N, 6 55 0 E, which is Riksveg 5 1240, 6856 Sogndal, southern Norway.