Ergonomics Guideline for VDT (Visual Display Terminal) Furniture Used in Office Work Spaces. BIFMA has developed a guideline for furniture, intended for computer use in the USA and Canada, by applying the measurable principles and design requirements of ISO 9241 parts 3 ("Visual display requirements") and 5 ("Ergonomic requirements for office work with visual display units"). BIFMA has not attempted to develop an ergonomic standard of its own. Instead it has chosen to provide a guideline that applies ISO principles. We have attempted to include every measurable principle and design requirement in ISO 9241 parts 3 and 5 that affects furniture.