There are two different excel files - one for upload products, and the other for any other product type.
Obviously, for upload product, you have no idea the size of the page uploaded by the customer, so the excel is provided with x and y dimensions of each page in the uploaded document in mm (clearly noted in the column header on row 43 of the info tab.)
For any other document type, you are in control of it by uploading a static document, or defining the dynamic document - so you know the size and don't need it in the excel.