The structural model of I/S was proposed. The I/S structures are divided into some groups by the number of I which exists between S and S. The structural types were defined as 0, 1, 2, 3, n. In the case of type 0, the structural model is defined in the range of 0-50 S% and the SS sequence is allowed in the nearest neighbour case of S and S. The structural model of type 1 is allowed in the range of 0-100 S% and the SIS sequence is recognized in the nearest neighbour case of S and S for 0-50 S%. The structural type 2 was defined in the range of 0-33 S% and the SIIS sequence exist in the nearest neighbour. The structural type 3 was defined in the range of 0-25 S% and the SIIIS sequence is recognized in the nearest neighbour case of S and S. Generally, the SI...IS sequence is recognized in the nearest neighbour case of S and S. The structural type of 1, 2, 3, ..., n correspond to Reichweite 0, 1, 2, 3, ...n, respectively. The theoretical X-ray diffraction profile of I/S proposed by I/S structural model were calculated. By using of positions three characteristic X-ray profiles, the diagram for identification of I/S structure was obtained. Using the diagram for natural specimen of I/S, the good results were obtained.