Scenario: =008 171126 t 20172016at\135\e\\\\\\\\\\vleng\d Change 008 position 6: 't' --> to 'p' Turn to =008 171126 p 20172016at\135\e\\\\\\\\\\vleng\d Solve by... (1) Edit Subfield Data Field 008 Position: 6:1 (Position: length) (MarcEdit starts counting at zero) Find: t Replace with: p (2) Using regular expression Find : (=008.{2}.{6})(t)(.*) Replace : $1p$3 Note: MARC starts its count at zero and regular expression at 1