In the case of the FAI/CNT militia, they were called Delegates
it gets very complicated when you start to try and work out how the command structure worked, as everything was done by committee.
Traditional army hierarchies in the militias were openly discouraged. Leaders in the militias carried no badge or insignia of rank, and were addressed by the militias as equals, not as superiors. Leaders were not saluted, and were called "Comrade" and not "sir". Orders could be challenged, and militia leaders and delegates had to explain the reason behind a particular order, rather than expecting blind acceptance!!!!
Organisation was done on a decimal basis, the basic group consisted of 10 men. then 100, 500 etc. a column could have anything from 1000 to 10,000 militiamen in it. Regular army officers were seconded to the militias as technical advisors, but were not trusted, and often ignored.
The committees of delegates actually voted whether to accept orders or not!!!!