No, that's quasi-elastic scattering. DIS was done, for example, by HERA, an elctron-proton collider. SLAC did it in 1968 and essentially discovered the quarks.

No, that's quasi-elastic scattering. DIS was done, for example, by HERA, an elctron-proton collider. SLAC did it in 1968 and essentially discovered the quarks. Of course there is always a measurement limit. Current limits for the size are "smaller than 1e-19m". That's why I wrote "as far as we know", as we have no evidence that they are not point-like, and we have rather strong limits.