Examples of two ring-like clouds as per the visual classification method. Left: J-bubble, cloud ID 238. Right: J-filament, cloud ID 3148. The cloud identification numbers (cloud IDs) can be used to identify the cloud structure from the main catalogue (Table A.1). The images are integrated intensity (moment 0) maps of the ¹³CO (2–1) transition. The numbers in the bottom-right corner of the images represent the J₁ and the J₂ moments, respectively. The colour bar represents the ¹³CO integrated intensity in K km s⁻¹. The white contour represents the cloud edge. The white circle at the bottom left of the figure represents the telescope beam size. The black ellipse on the second image represents an artistic impression of the visualised ring.