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 systems mounted a large market trial in Los Angeles in partnership with NBC and Public Broadcasting Service (PBS) Public television. Services premiered simultaneously on station KNXT (now KCBS-TV), KNBC and KCET in Los Angeles. All three services included an array of local news and information services. KCET's service also included service components for use in schools. Later, an official North American standard of teletext, called NABTS (North American Broadcast Teletext Specification) was developed in the early 1980s by Norpak, a Canadian company. NABTS provided improved graphic and text capability over WST, but was quite short-lived. This was mainly due to the