Curious about marking on board

I noticed an interesting marking on the bottom of the board, just above the "Assembled in Italy" silkscreen and the UL 94V-O flammability component mark:


The actual image appears brown on the blue background... no copper, no resist, no plating. Anyone know if this is a test pattern to check on the board manufacturing process, another regulatory mark I hadn't seen before, or...?

The first symbol is the Logo of the ALBA PCB Group.