Inserting or editing an OnMerge Image brings up a multi-page (tabbed) dialog box. The dialog is initially open to the first File Names page that allows you to enter the formulas for what the image file's name will be for each record.

The lower section of the dialog allows you to enter the formulas that determine the file name for each row (record) of the data source. The upper section is a preview of the result of those formulas is any given row of the data source.

Upper (Preview) Section of the Dialog

The preview section of the dialog allows you to see a thumbnail preview of the image file for each record in the data source. Each row (record) in the data source can be associated with a different image, so the preview show is the one for the row number shown in the white area. To review the image for each data row, press on the forward and backward navigation buttons, or enter a record number in the white space in the middle of the navigation arrows. Notice that the image and the Image File Name are updated for each record as you cycle through them.

Both the image and Image File Name are also updated immediately when you change the data in the File Name Parts section below.