Answer:
Referendum
Step-by-step explanation:
ordinance of Secession was a document that's crated to explain the reason why Several southern states decided to secede from United States in 1860.
In order to reach that conclusion, each of those states held a Referendum.
During a referendum, a state gathers all of the electorates that represent the people of that states and make a direct/universal vote to a certain proposal. Those southern states decided to held this referendum because difference in opinion about slavery between southern states and northern states at the time.