Who can initiate an optional referendum at the national level?

Georgian constitution; Articles 5, 67, 74, 102

Article 74.1

At the request of the Parliament of Georgia, ofnot less than 200,000 electors or on his/her own initiative the President ofGeorgia shall schedule a referendum concerning the issues determined by the Constitutionand the Organic Law within 30 days after receiving such a request.

Law on Referendumof Georgia (2003)

http://www.venice.coe.int/docs/2003/CDL(2003)077-e.pdf

Article 9.Appointing the referendum 

1. Presidentappoints the referendum; 

2. CentralReferendum Commission prepares and conducts the referendum.

Article 10.Initiative group for arranging the referendum 

1.If the voters initiate the conduct of referendum, an initiative group isformed. First name, last name and place of residence of each member of theinitiative group should be indicated on the group list. The group shouldclearly and specifically define the issue proposed for the referendum.