"sku","File 1", "File 2", "File 6", "File 7"
"00123","www.site.com/path/to/file/file.pdf","www.site.com/path/to/file/file.pdf",,
"00124","www.site.com/path/to/file/file.pdf",,"www.site.com/path/to/file/file.pdf",
"00125",,"www.site.com/path/to/file/file.pdf",,"www.site.com/path/to/file/file.pdf"