Specifies that the new row is to be added to the table in the
order specified in the sort information record. A TBSORT must have
been performed for this table before use of this keyword. For tables
with keys, the table is searched to ensure that the new row has a
unique key. If a row with the same key already exists, the row is
not added. This keyword is ignored if the table has never been sorted.
If this keyword is omitted, any existing sort information record is
nullified and to restore it, another TBSORT is required. When
a newly inserted row has sort field names equal to the sort field
names of an existing row, the insertion is made after the existing
row.