Just read a Wikipedia article about ogg and found out that new file extensions
were created in RFC 5334:
In September 2008, RFC 3534 was obsoleted by RFC 5334, which added content
types video/ogg, audio/ogg and filename extensions .ogx, .ogv, .oga, .spx.
Seems to me that BonkEnc should be using these new file extensions instead of
the now obsolete .ogg extension.
No, .ogg is still the recommended file extension for Vorbis audio files in RFC
.oga is for Ogg files containing other codecs than Vorbis or Speex only.