File names should only use lower case characters and hyphens and should have only one file extension that indicates the format of the file. You should avoid using what are known as “special characters” in your file names such as punctuation, underscore, spaces, or other nonalphanumeric symbols. The only exception to this is regarding SAS transport files to the FDA, in which they will allow underscores. Internal corporate naming conventions that include date or version tags in the file name are not helpful to the review agency and increase the length of the file name. Consider removing these prior to adding the files to your eCTD submission.