Currently you can only replace an entire string of a fixed length field using MARC modification templates. It would be a great enhancement to be able to update specific positions. For example, if I need to update the place of publication in the 008, I only want to change positions 15-17, not the whole string. Likewise, if in the leader/000 I need to change the position 6 type of record, I don't want to have to replace the entire string. As it is now, users have to the export the records to something like MARCedit, do the work, and then overlay. It would be wonderful to be able to do this all cataloging without leaving Koha.