DMNFTF — Can decision tables have zero inputs?

It is not clear from the spec whether it is valid to have a decision tables with no inputs. In such a table all rows would always be true (i.e. facts, rather than rules). This would be useful on occasions, e.g. for generating a list of items to be filtered in subsequent decisions (although it would be possible to provide the same functionality using boxed contexts or raw FEEL).

Is this valid? If so we need to provide an example.
If not the spec needs to be clarified anyway.

0 input decision tables are explicitly allowed in beta3 (there is no example)