IEC 60601-2-29:2008 establishes requirements to be complied with by manufacturers in the design and construction of radiotherapy simulators; it does not attempt to define their optimum performance requirements. Its purpose is to identify those features of design that are regarded, at the present time, as essential for the safe operation of such medical electrical equipment. It places limits on the degradation of medical electrical equipment performance beyond which it can be presumed that a fault condition exists, for example a component failure, and where an interlock then operates to prevent continued operation of the medical electrical equipment. This third edition cancels and replaces the second edition published in 1999. This edition constitutes a technical revision, which brings this standard in line with the third edition of IEC 60601-1 and its collateral standards.