In general, transparent, non-proprietary formats are best. When a proprietary format is submitted to the archive (such as a Microsoft Word document) an accompanying plain text file is also required. It is assumed that the scientists of the future will at least be able to make sense of regular ASCII bytes even if the proprietary software and support ceases to exist.
For general use, transparent, non-proprietary formats are preferred. When submitting proprietary formats (like a Microsoft Word document), an accompanying plain text file is required. It's assumed that future scientists will be able to understand basic ASCII characters even if the software and support for the original format disappears.