The central government is going to prepare within the next three months the modalities for revision of criteria for including communities in the Scheduled Tribes, union Tribal Affairs Minister Jual Oram said here on Saturday.Addressing a seminar on preparation of a vision document for Scheduled Tribes of the northeast at Shilpagram in Guwahati, Oram said around 1,000 communities have applied for inclusion, but all have been kept on hold as the government wants to go for a revision of criteria. Six communities in Assam have been demanding Scheduled Tribe status -- Tai Ahom, Maran, Matak, Koch Rajbongshi, Chutia and the Tea Tribes.There are about 580 communities in the Scheduled Tribe list as of now.Oram said the task was a multi-disciplinary mechanism which requires involvement of various authorities. "The government of India cannot do it alone," he said.Oram, however, said the case of the six tribes of Assam was "positive"."Chances are there that before the Assam assembly elections scheduled for early next year, the whole process will be completed," he said.