Due to the track time differences, it is difficult to make an official determination of where one song begins and where one ends (although the band's digital box set The Complete U2 and the 2008 remastered version of Boy standardized the original European pressings' running times).
The 1998 single "Sweetest Thing" features a live performance of both songs from the War Tour, but only "An Cat Dubh" is listed.
The song was written about a short relationship that lead vocalist Bono had with a woman while split from his girlfriend (now wife) Ali Hewson.
Additionally, there is a sustained sound heard during the two tracks that was achieved by guitarist the Edge playing his guitar tuner and producer Steve Lillywhite adding several effects.
In 2010, U2 manager Paul McGuinness said that "An Cat Dubh" remained one of his favourite live tracks, describing it as "symphonic", adding that it had "very big musical ambitions."
He stated that the later compositions "Bad" and "One" were "the songs in line of descent from [An Cat Dubh]" because of their ability to continually grow in the live setting.