  In this paper, we study the norm-based robust (efficient) solutions of a
Vector Optimization Problem (VOP). We define two kinds of non-ascent directions
in terms of Clarke's generalized gradient and characterize norm-based
robustness by means of the newly-defined directions. This is done under a basic
Constraint Qualification (CQ). We extend the provided characterization to VOPs
with conic constraints. Moreover, we derive a necessary condition for
norm-based robustness utilizing a nonsmooth gap function.
