The Big5 codec provides conversion to and from the Big5 encoding. The code was originally contributed by Ming-Che Chuang <firstname.lastname@example.org> for the Big-5+ encoding, and was included in Qt with the author's permission, and the grateful thanks of the Qt team. (Note: Ming-Che's code is QPL'd, as per an mail to email@example.com.)
However, since Big-5+ was never formally approved, and was never used by anyone, the Taiwan Free Software community and the Li18nux Big5 Standard Subgroup agree that the de-facto standard Big5-ETen (zh_TW.Big5 or zh_TW.TW-Big5) be used instead.
The Big5 is currently implemented as a pure subset of the Big5-HKSCS codec, so more fine-tuning is needed to make it identical to the standard Big5 mapping as determined by Li18nux-Big5. See http://www.autrijus.org/xml/ for the draft Big5 (2002) standard.
James Su <firstname.lastname@example.org> <email@example.com> generated the Big5-HKSCS-to-Unicode tables with a very space-efficient algorithm. He generously donated his code to glibc in May 2002. Subsequently, James has kindly allowed Anthony Fok <firstname.lastname@example.org> <email@example.com> to adapt the code for Qt.
See also Text Codecs: Big5, Big5-HKSCS.