There are 3 lengths of these types of undergarments;

Drawers: undies that reach to mid thigh

Breeches: undies that reach just above or below the knee

Pantaloons: undies that are below the knee to the ankle

I made these breeches for summer wear to keep my legs from rubbing together beneath my skirts when I didnt feel like, or it was too hot to wear binding foundation garments.
I LOVE them. Cool freeing and breezy. I used one of my vintage slack patterns, upped the sizing, gathered the excess and there you go. The side stays open, and is only closed by the two buttons. I use mostly a light weight cotton for easy washing, and for wear. These were all made from scraps.