Strong even boundary slope conjecture for prime non-torus knots

Let $K$ be a prime non-torus knot and let $E(K)$ be its exterior. A properly embedded orientable incompressible and boundary incompressible surface in $E(K)$ may have a boundary slope measured on the boundary torus of $E(K)$. Strong even boundary slope conjecture. For any prime non-torus knot $K$, there is a properly embedded orientable incompressible and boundary incompressible surface, which is not a Seifert surface, in the exterior $E(K)$ with boundary slope an even integer. The paper presents this as a stronger version of the Even Boundary Slope Conjecture and states that it remains unknown.