The iiindex_columns Catalog

For indexes, any columns that are defined as part of the primary index key will have an entry in iiindex_columns. For a full list of all columns in the index, use the iicolumns catalog.

Column Name	Data Type	Description
index_name	char(256)	The index containing column_name. Must be a valid name.
index_owner	char(32)	The index owner. Must be a valid username.
column_name	char(256)	The name of the column. Must be a valid name.
key_sequence	smallint	Sequence of column within the key, numbered from 1.
sort_direction	char(8)	Defaults to A for ascending.