This part of ISO 14915 establishes design principles for multimedia user interfaces and provides a framework for handling the different considerations involved in their design. It addresses user interfaces for applications that incorporate, integrate and synchronize different media. This includes static media such as text, graphics, or images, and dynamic media such as audio, animation, video or media related to other sensory modalities. Detailed design issues within a single medium (e.g. the graphical design of an animation sequence) are only addressed as far as they imply ergonomic consequences for the user. This part of ISO 14915 gives requirements and recommendations for the ergonomic design of multimedia applications mainly intended for professional and vocational activities such as work or learning. It does not specifically address applications outside this area such as entertainment, although some recommendations can also be applicable in such domains. This part of ISO 14915 is applicable to software aspects related to multimedia user interfaces and does not address hardware or implementation issues. The ergonomic requirements and recommendations described in this part of ISO 14915 can be realized through very different techniques, e.g. the delivery system, a scripting language, or the application. The focus of this part of ISO 14915 is on multimedia presentation issues. Multimodal input which uses different media such as speech in combination with pointing for entering information is not considered in the recommendations provided.