Editing Test Card F (section)

====BBC HD channel variant ("Test Card X") ==== 
{{anchor|testcardx}}
A [[1080i|1080 line]] variant of Test Card W (sometimes referred to unofficially<ref name="Quested_quote">{{cite web|author=Quested, Andy |work=BBC Internet blog|url=https://www.bbc.co.uk/blogs/bbcinternet/2008/12/a_christmas_present_from_the_h.html|access-date=2013-12-21|title=A Christmas Present from the HD Channel!|quote=The test card seems to have been given the name "Test Card X" but not by us, it is in fact a modified high definition version of test card W}}</ref> as '''Test Card X''') was used on the now-defunct [[BBC HD|BBC HD channel]]. It could be viewed every two hours as part of the BBC HD preview slot. When viewed, it was enhanced with 5.1 surround sound tests. A [[Black & Lane's Ident Tones for Surround|BLITS]] tone is played alongside, which plays test tones at different frequencies from each of the different surround sound speakers, with markers (such as L, R, C, LFE, Ls, Rs) appearing inside some of the grey boxes of the testcard.<ref name="Quested">{{cite web|author=Quested, Andy |work=BBC Internet blog|url=https://www.bbc.co.uk/blogs/bbcinternet/2008/12/a_christmas_present_from_the_h.html|access-date=2011-12-14|title=A Christmas Present from the HD Channel!}}</ref> BBC HD closed in March 2013; therefore Test Card X is no longer regularly broadcast. Test Card X did however make an appearance on the lunchtime edition of ''Sportsday'' on the [[BBC News (British TV channel)|BBC News channel]] on 18 January 2023, in place of a slide intended to show the [[BBC Sport]] website.<ref>{{cite web | url=https://cleanfeed.thetvroom.com/16533/bloopers/the-test-card-puts-in-an-unscheduled-appearance-on-sportsday/ | title=The test card puts in an unscheduled appearance on Sportsday | date=18 January 2023 }}</ref>