Editing List of BBC test cards (section)

==Test Card X==
The high-definition version of Test Card W is visually similar but officially lacks a designation letter. This version is often referred to as Test Card X, but this is not a designation which the BBC recognises.<ref>{{cite web |last=Quested |first=Andy |title=A Christmas Present from the HD Channel! |url=https://www.bbc.co.uk/blogs/bbcinternet/2008/12/a_christmas_present_from_the_h.html |date=17 December 2008 |publisher=[[BBC]] |accessdate=14 August 2009 }}</ref> It is designed for use on [[high-definition television|high-definition]] TV services, & had been included a part of [[BBC HD]]'s preview loop since November 2008 (though it had been in use internally at the BBC for several years prior) until the channel's closure in March 2013.