ABAP_DESCRIPTION The table spfli_tab> is a hashed table with an unique primary key and two non-unique sorted secondary keys.
The first LOOP> takes place without a key specification. The table output is in the order in which the table was filled, that is, sorted by the fields specified after ORDER BY> in the SELECT> statement.
The other two LOOP> loops are performed with each of the secondary table keys city_from_to> or city_to_from> specified.