Each alternate file can have the following properties:
Enabled: If checked, VIEW will generate an extra image for this area
Format: Image format properties for the alternate file
Image format: Output image format
Base filename: Base output filename
Prepend parent area filename: If checked prepends parent AREA filename, else "Base filename" will be the full output filename (without extension)
Load Preview: As there can be up to 8 alternate files, generating preview for all can be slow. If you want to see area previews, click on this button