Colour symmetry. 2(12) and 2i mean rotations of order 2. (12) means that the colours white and blue are interchanged; i means the identity. Mirrors are represented by red lines.
This is an example of the case stated in the fourth row of the table in Section 4.4 (Figure 12, «p2mm») in
Wallpaper groups. Tiles: Brasil, Brasilia Palace Hotel - p2mg