Issues of sub-national referendums regulated at the national level

Sudan
Answer
None
Source
The Interim National Constitution of the Republic of Sudan (from 2005) http://www.mpil.de/shared/data/pdf/inc_official_electronic_version.pdf
The National Elections Act from 2008 (Act no. XI of 2008)http://www.cmi.no/sudan/doc/?id=1035
Comment
No provision was found in this regard