We propose a configuration of D-branes welded by analogous orbifold op
eration to be responsible for the enhancement of SO(2n) gauge symmetry
in type n string compactified on the D-n-type singular limit of K3. E
vidences are discussed from the D-n-type ALE and D-manifold point of v
iew. A subtlety regarding the ability of seeing the enhanced SO(2n) ga
uge symmetry perturbatively is briefly addressed.