The predicate function line_exists can be considered as a short form of the statement READ TABLE with the addition TRANSPORTING NO FIELDS following by sy-subrc being checked.
   
The predicate function line_exists cannot be used to determine the row number in a table index of a search key, since table expressions do not fill the system field sy-tabix.

Serkan AKKAVAK
Computer Engineer
SAP Department Deputy Manager
Contact : serkurumsal@yandex.com