Issues in relation to which referendums are optional at the national level

Angola
Constitution(2010), Article 161 (j) http://aceproject.org/ero-en/regions/africa/AO/constitution-of-the-republic-of-angola-2010/at_download/file
Article 161 (j) Within the political and legislative sphere, the National Assembly shall be responsible for: Proposing to the President of the Republic that referendums should be held on relevant matters of national interest