Vintage blue button down shirt sheath dress

adorable 1960s sleeveless structured dress. Fabric feels like wool. Buttons halfway down. Built in belt that buttons in back. Metal zipper. A well made piece in very good condition. Only flaw I found is possible from moth damage in one small spot, which is common in vintage wool clothing. Tag says it's size 11, before the 80s, odd numbers were petite sizes. I would guess this is a modern size 8 petite, but check the measurements: pit to pit 28", waist 29" around, length 35"