Hi brash - There are several different kinds of perpendicular cases, and it's not really very clear to me which kind you're actually referring to, maybe if you could include a graphic that would help illustrate that might help.

Perp object snap will find a perpendicular for a line from the previous picked point onto a curve. So for example when you're drawing a line and placing the second point of the line, it will find a point perpendicular to the curve close to your mouse from the first point of the line that you picked.

When you are doing a construction line relocate, the "previous point" in that case will be the first point that was picked in creating the construction line.

But I'm not sure if you are talking about having perp snap engaged for the cline relocation step itself, or are you talking about doing some perpendicular snap after you have finished relocating the cline?

If you want to have a perpendicular that's coming off from a curve like Pilou shows above, then that's done with perpendicular "straight snap" - you need straight snap turned on for that one to get triggered. Perp object snap controls kind of the other direction, when you are approaching a curve from a different point not when you are going away from a curve.

I think I need some more information from you to clarify what you're looking for though, I don't understand which particular kind of snap you're looking for in combination with relocating the cline.

- Michael