Are referendum results binding?

Sudan
Answer
Optional referendum - always
Source
The Interim National Constitution of the Republic of Sudan (from 2005) http://www.mpil.de/shared/data/pdf/inc_official_electronic_version.pdf
ReferendumArt. 217 (3) Any resolution which has achieved the consent of the people by referendum shall have authority above any other legislation. It shall not be annulled save by another referendum.