Older Sky HD boxes have both HDMI and component outputs; however, of the two, only the HDMI connection supports HDCP - high bandwidth digital content protection - which is designed to make copying content in high definition move difficult.
HDMI is now a standard connection on high definition televisions but older equipment may only support component video. It is thought Sky left such connections on earlier models for this reason; in 2005, Sky told Digital Spy that all programming would be available over the component outputs.
Sky has amended the Sky HD user guide with an explanation stating that "a minor adjustment" has been made "by removing the HD analogue component video connection".
It added: "This change was made to help prevent the illegal copying of HD programmes and movies, and enable Sky to continue to bring you quality entertainment."
The broadcaster has explained the change and told Digital Spy it would not cause a problem for subscribers.
> Discuss the move in the DS Sky HD forum