Duty Committee Member
During a convention there's a hierarchy for passing questions up the chain of command :-)
A convention member may ask a gopher or steward for assistance with something and if they can help, that's good. It may need to get passed up the chain of command to Ops; but if it is a tricky decision, requires a large financial outlay or just needs a convention policy decision, then it gets passed up to the Convention Committee, in the person of the Duty Committee Member (DCM).
The DCM is responsible for making any tough decisions during the con (whether to ask someone to leave the convention for breaching the rules, whether to authorise a large payment for damages, handling a particularly irate member etc.).
During the day the DCM is often the convention chair but since they can't be expected to be on duty 24 hours a day, other responsible committee members take over some of the shifts.
The DCM is not a replacement for having someone responsible for talking to the hotel/site but may have to handle issues if it is late at night, if the hotel liaison is busy doing something else, or if it is urgent and there's no time to find the hotel liaison.
It is common, on the last day of the convention, at the closing ceremony, to hand the DCM badge to someone from the following year's Eastercon and tell them that they are responsible for the rest of the evening as the current committee are going to have a meal, head to the bar or just get an early night as they are worn out!