I Do, I Do, I Do, I Do, I Do Rock Me

After the flop of ½So Long½, ½I Do½ made the Top 5 in most countries (#15 in the US) - except in the UK (only #38). ½Rock Me½ was the main B-side, except in North America (½Bang-A-Boomerang½), Holland (½So Long½, where that song hadn’t been released as A-side) and Brazil (a belated 1976 release b/w ½Fernando½, where the song wasn’t released as A-side).
In Peru the sides were merely switched.
In Turkey, ½I Do½ was coupled with ½SOS½, but is unclear which side is the A-side and when the single was released - see SOS.

½I Do½ appeared on ½Greatest Hits½ soon after the single release.
After ½I Do½ had hit #1 in Australia and New Zealand, the single was re-released there with ½Rock Me½ as A-side, reaching #4 and #2 respectively.
These successes and the fact that the track was in the setlist of the world tour in 1979 apparently resulted in the track appearing ½Greatest Hits Vol. 2½, as the only track not recorded between the years 1976 and 1979.

(Discogs)