You can read the entire text here: Letter to the Bishop's Conferences on "the Name of God"
Presumably this would retroactively effect some popular liturgical music that has been used in many English speaking parishes following the Council, including by the likes of Fr. Dan Schutte, S.J.
[Thanks to a good friend of the NLM for bringing this foward and for acquiring the source material above. The gist of the story first appeared on the blog Communio this past weekend.]