Content multiplexed in Ogg now requires a Skeleton track
As per a recent decision[1] on the Xiph.Org Foundation, all content in Ogg (save for basic Vorbis or Speex streams) are to have an Ogg Skeleton[2] track.
What that means is that for VLC to become a compliant encoder, it would need to verify that when the user chooses Ogg as the container format, unless s/he didn't pick audio-only Vorbis or Speex from the drop-down, a Skeleton bitstream would need to be multiplexed into the resulting Ogg file.
Example Skeleton code (under BSD license) may be found at [3][4].
Feel free to contact the ogg-dev[5] mailing list in case of questions.
[1] http://www.ietf.org/internet-drafts/draft-goncalves-rfc3534bis-00.txt [2] http://wiki.xiph.org/index.php/Ogg_Skeleton [3] https://trac.xiph.org/browser/trunk/speex/src/skeleton.c [4] https://trac.xiph.org/browser/trunk/speex/src/skeleton.h [5] http://lists.xiph.org/mailman/listinfo/ogg-dev