1/4 BJD & Fashion Doll
For BJDS this size is 40cm Slim MSD. For Western Fashion Dolls, the term is 16" Fashion Doll. Though different in looks, they are very similar in size and can share patterns!
If you're looking for MSD/MDD dolls, go here
The default settings on sizing is designed to best fit Fairyland Minifees and Ellowyne but has a lot of cut variations so you can tuck in the waist for wasp-waisted dolls like 16" FR/Poppy dolls, widen the chest for broad-shouldered dolls like Kid Delf, and adjustable bust sizes.