The index table itself can contain the following columns. The order of the columns in the table is not significant and the names of the columns are case-insensitive. Other columns may be included in the index table but they are not defined by this convention.
IND_POINTER (required) (integer)This column gives the row number (starting with 1 not 0) of the first event in the indexed table that falls within this index bin.
IND_LENGTH (optional) (integer)
This column gives the number of rows/events in the indexed table that are in this index bin. If the IND_LENGTH column is not given then the number of events in each bin can be assumed to be equal to the difference between the consecutive IND_POINTER column values. For example, if the IND_POINTER value for the 2nd index bin is 50 and the IND_POINTER value for the 3rd bin is 70, then there must be 70 - 50 = 20 events in the 2nd index bin. Unless the FORELINK keyword is specified, it is assumed that the events in the indexed table have been sorted so that the events in each index bin all occur in rows IND_POINTER through (IND_POINTER + IND_LENGTH - 1) of the indexed table.
colname_MIN (optional) colname_MAX (optional)
These 2 columns give the minimum and maximum value of the specified column in the indexed table for all the events in this index bin. This pair of columns may be repeated for every column in the indexed table. The data type of these columns should be the same as the data type of the original column in the indexed table.
IND_STARTn (optional) (double-precision floating-point)
This column should only be present when the size of the index table has been compressed by eliminating all rows that would have a value of IND_LENGTH = 0. The value in this column gives the starting value of the index bin that would otherwise have been implied by the row number and the ISTRTn and IDELTn keyword values. (See example 7, below).