Discriminant loci of ample and spanned line bundles

Let (X,L,V)(X,L,V) be a triplet where XX is an irreducible smooth complex projective variety, LL is an ample and spanned line bundle on XX and V⊆H0(X,L)V⊆H0(X,L) spans LL. The discriminant locus D(X,V)⊂|V|D(X,V)⊂|V| is the algebraic subset of singular elements of |V||V|. We study the components of D(X,V)D(X,V) in connection with the jumping sets of (X,V)(X,V), generalizing the classical biduality theorem. We also deal with the degree of the discriminant (codegree of (X,L,V)(X,L,V)) giving some bounds on it and classifying curves and surfaces of codegree 2 and 3. We exclude the possibility for the codegree to be 1. Significant examples are provided.