the australian government participated in a number of regional broadcasting conferences which concluded with it signing the 1975 regional broadcasting agreement in 1975. the plan commenced on 23 november 1978. its principal feature was a raster of 9 khz channel spacings compared to the 10 khz plan which had prevailed in australia since 1935, in line with international standards. as a consequence there were 12 additional channels available for allocation in australia with but small increase in adjacent channel interference. together with the increased spectrum opportunities provided use of am directional antennas, a significant number of new services were able to be introduced, satisfying to some extent, the rapidly increasing demand for new services which ultimately could only be satisfied by the release of the fm radio band for broadcasting purposes.