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

Uzbekistan
Constitution 1992
http://www.gov.uz/en/constitution/
Article 9. Major matters of public and state life shall be submitted for anation-wide discussion and put to a direct vote of the people (a referendum).The procedure for holding referendums shall be specified by law.
Law ofthe Republic of Uzbekistan about the Referendum of the Republic of Uzbekistan
English version is available at: http://cis-legislation.com/document.fwx?rgn=754
Article 1. Referendum of theRepublic of Uzbekistan
Referendumof the Republic of Uzbekistan (further - the referendum) national vote ofcitizens on the most important issues of public and state life for the purposeof adoption of the laws of the Republic of Uzbekistan and other decisions.
Thereferendum along with elections is direct expression of the will of the people.The decisions accepted by the referendum, have the highest legal force and canbe cancelled or changed only by the way of the referendum.
Thereferendum is carried out in all territory of the Republic of Uzbekistan.
Article 2. Questions which arenot the subject of the referendum
Questionscannot be the subject of the referendum:
aboutchange of territorial integrity of the Republic of Uzbekistan;
aboutthe Government budget of the Republic of Uzbekistan and taxes;
aboutamnesty and pardon;
aboutemergency and urgent measures on providing the public order, health and safetyof the population;
aboutaccomplishment of the obligations following from international treaties of theRepublic of Uzbekistan;
connectedwith appointment and release of officials.
Article 3. The circumstances excludingcarrying out the referendum
Thereferendum is not carried out in the conditions of the wartime or the emergencystate entered in all territory of the Republic of Uzbekistan, and also withinthree months after the termination of the wartime or cancellation of emergencystate.
Thereferendum is not carried out within the year after official publication ofresults of the referendum with same on content or in sense the formulation ofthe question.