1. A computer-implemented method for converting, in an OSI (Open System Interconnection) network name tree, an MOI (Managed Object instance) identification name, into an index, wherein "n" denotes a number of MOI in the OSI network name tree, "m"=.vertline.r.vertline..div.N, "[x]" denotes an integer rounded up from a value x and "XOR" denotes an exclusive OR, said method comprising the steps of: dividing an MOI identification name into m blocks Bi (1.ltoreq.i .ltoreq.m), wherein each block N includes bits, N=log.sub.2 n, wherein a value 0"is applied to an m-th block B.sub.m if an insufficiency of a bit occurs in the m-th block B.sub.m ; performing an XOR of a j-th bit N.sub.ij (1.ltoreq.j N) of each block B.sub.j as C.sub.j =b.sub.1j XOR b.sub.2j XOR b.sub.3j. .. XOR b.sub.mj ; making an N bit sequence C.sub.1 C.sub.2 C.sub.3. .. C.sub.N as an index of an MOI identification name by sorting said calculated value C.sub.j from C.sub.1 to C.sub.N ; allotting the index of the MOI identification name to a corresponding MOI contained in the OSI network name tree; and performing management operations on at least one MOI by referencing at least one allotted index.