Question About Plate Blocks..?

Hi guys..Tell me, this Scott # 507 block has the inscription gutter paper on it, but most plate blocks I see have inscription plus gutter paper on one other side..Is this considered a block or a plate block..?

The part of the plate block here that goes with the vertical inscription on the right is the top horizontal imperforate side. Some BABN stamps were issued with imperforate straight edges on some sides. Thus, this is considered an upper right plate block. See footnote on bottom of page 170 in the Unitrade Canada catalogue which describes this further. The picture below shows how a matched set looks like with all four different corner plate block positions. The upper right and upper left corner plate blocks have imperforate top horizontal straight edges while the bottom right and bottom left corner plate blocks have perforated bottom horizontal margin edges.