It has become very common in the current information society to talk about “open” and to use this term as a quality mark. Open standards, open source software, open archives, open formats etcetera are all very much promoted. In this contribution, we would like to focus on the file structure of documents such as texts, spreadsheets and presentations, and more specifically on the Open Document Format. ODF is becoming increasingly popular for many reasons, but it also is the first document format for use in office suites that has unique features built in (as of version ODF 1.1) for persons with a reading impairment such as low vision, blindness or dyslexia.