Regarding Kelsen's original use of the term Grundnorm, its closest antecedent appears in writings of his colleague Adolf Merkl at the University of Vienna. Merkl was developing a structural research approach for the understanding of law as a matter of the hierarchical relationship of norms, largely on the basis of their being either superior, the one to the other, or inferior with respect to each other. Kelsen adapted and assimilated much of Merkl's approach into his own presentation of the "Pure Theory of Law" in both its original version (1934) and its revised version (1960). For Kelsen, the importance of the Grundnorm was in large measure two-fold since it importantly indicated the logical regress of superior relationships between norms as they led to the norm which ultimately would have no other norm to which it was inferior. Its second feature was that it represented the importance which Kelsen associated with the concept of a fully centralized legal order in contrast to the existence of decentralized forms of government and representing legal orders.