The EDIT Switch, toggled by <PF2>, controls whether the actual row data displayed on the lower part of the DK1TDRVC screen may be edited. When this switch is set to EDIT, data is transferred directly back and forth between the screen and the table row in memory. This is convenient for rows containing only displayable characters, but definitely not a good idea for rows with binary data.
When this switch is OFF, all non-display characters are converted to periods, which can be safely displayed, and direct editing of the row data is disabled. Conversion commands are available to format data for editing in the upper-screen area and to move edited data back to the row. This is more work (though extra commands are provided to simplify common sequences), but both safer and more powerful than the direct edit. It is the default mode.