An index of an internal table, administrated by the ABAP runtime environment. There is a primary table index for index tables and secondary table indices for the administration of sorted secondary table keys. The line numbers of every table index start at 1 and run consecutively and with no gaps, up to the current number of rows in the table. If necessary, the physical index is changed to a logical index, which causes an increased runtime demand. The logical index is created in precisely the moment in which a row is inserted before another row, the sequence of table rows is changed, or if any row except for the bottom row is deleted.