Internal path tool - Custom seam allowance

Hi all. I am wondering how exactly work the internal path tool. I mean in dialogue box you can choose between type - internal path(this one, I get it) or custom seam allowance. How does exactly work the custom seam allowance and what is used for? If someone make it through I’d be happy to understand! thanks

The custom seam allowance only takes away the choice of line type. It’s preset to dash-dot-dash. So if this is the type of line you’d like for your fold line on the pattern, you may as well use it. Other than that, they seem identical to me :smile: