The emotional dramaturgy and the aesthetic design are useless if the iTV format and the iTV application are ultimately rejected by the viewer due to poor useability. It is therefore necessary to measure the design of the contents and graphics on the basis of the recognised rules of good useability. Refer to the literature and the standard ISO 9241-10 for interactive systems of all types. The standard defines 7 general rules:

1. Task appropriateness (complete, correct, justifiable effort)
2. Scope of self-description (comprehensible, help system)
3. Conformity to expectation (uniform, tailored)
4. Error tolerance
5. Controllability
6. Ease of individualisation
7. Learning suitability

These approaches can be essentially applied to ITV. In individual cases adjustment to the peculiarities of the medium is recommended, e.g.:

• With regards to completeness, not to get on the wrong track in special cases
• Only offer ease of individualisation with good reason and then only to an appropriate extent
• Formulate a help system as a context-sensitive user guide

Furthermore, apply the most important rule: That interactive television revolves around entertainment. It must "be fun".