KEYEDIO files consist of three logical areas contained within one physical file: coarse tables, fine tables, and data. The size of these areas increases during the life of a file as records are added and deleted. The areas are not distinct from one another and are intermixed throughout the file. Each block of data in a KEYEDIO file contains information for a single type of area. Control information describing the block and how to access it is appended to the beginning of each block in the file.