I believe those extra marks are for when you're drawing a circle on a flat surface that's angled away from you. Example, drawing an oblique cube, you'll use the 45° ellipse, place that mark vertical on the side of the cube (not front or top of cube), center your circle where you want it, and use your pencil/pen to draw the circle. Viola.
Use the 60° one for isometric angled objects, so on and do forth.
canuckpopsicle in the post "Are the marks on the ellipse template the only possible minor axis? Explain question in the comments"
2021-12-06 09:27
I believe those extra marks are for when you're drawing a circle on a flat surface that's angled away from you. Example, drawing an oblique cube, you'll use the 45° ellipse, place that mark vertical on the side of the cube (not front or top of cube), center your circle where you want it, and use your pencil/pen to draw the circle. Viola.
Use the 60° one for isometric angled objects, so on and do forth.