If online communities open for a decision process they will have to decide what type of decisions can be made, what is their DecisionSpace.
Trivial example.: A community could decide that the only community decision is on the "community logo" ... that any member is free to suggest a logo within technical boundary conditions (width, height, format, copyright, ...) and if it gets a 2/3 majority of votes, it will replace the old logo. In this case "community logo" would be the only content of the DecisionSpace. Still the process of making this decision can get very complex.
Counter example. A community may be in a situation where it is impossible to decide to add a certain feature to the software. In case of such a decision it would be unclear who is responsible for doing it - it may need a development effort that has to be paid for. No budget is available. Such a decision may be outside of the DecisionSpace.
Of course, any decision that is illegal is also outside the DecisionSpace.