PACKED coefficient format is a dense unformatted file structure designed to minimize disk space usage. At the beginning of the file is a block of comments. Like a map file each comment is 80 bytes in length and all but the last comment begins with an asterisk (``*''). A minimum of one comment is required. Following the comment block is a sequence of records each composed of two parts. The first part is an integer array 100 elements long and the second part is a complex array 100 elements long. The record that is composed of these two array contains up to (surprize!) 100 reflections. The integer array contains the indices for the coefficient stored in the corresponding element of the complex array. The indices are packed using the formula:
This formula causes the restriction that no h, k, or l can fall outside the range of -255 to 256. I have not had the good fortune to have any problems with this limitation but virus people might.
Any element in the array of packed indices with a value of 0 should be ignored. An element of -1 signals the end of the list of reflections and no more reads should be performed on the file.