BBC Two until 23 October 2012, via the Ceefax teletext service. The BBC also offers audio description on some popular programmes for visually impaired-viewers as well as sign language interpretation on some of its programmes for deaf and hard-of-hearing viewers. The percentage of the BBC's total television output with audio description available is 10%, having been increased from 8% in 2008. Originally, programmes from BBC Two were shown in high definition on the dedicated BBC HD channel, alongside programmes from BBC Three and BBC Four, as well as some select series from CBBC and CBeebies. However, in plans outlined by the director
Teletext Services (XDS). NABTS was originally developed as a protocol by the Canadian Department of Communications, with their industry partner Norpak, for the Telidon system. It was similar to the European World System Teletext (WST, aka CCIR Teletext System B), but differences between the European and North American television standards and the greater flexibility of the Telidon standard led to the creation of a new delivery mechanism that was tuned for speed. First demonstrated in the United States in 1978, NABTS was the standard used for both CBS's ExtraVision and NBC's very short-lived NBC Teletext services in the mid-1980s. Station KSL-TV