DMNFTF — Decisions are said to have "inputs" and "outputs", however only the "inputs" are shown in the diagrams

The definition of "Decision" on page 23, section 5.2.1 defines "Decision" as an activity ("act"). It mentions a Decision has an "output" value, however, an "output" shape coming out from the decision activity is not shown in the diagrams.

It may be useful to draw and show an output shape coming out from the Decision box. That could be named "Decision output".

This suggestion applies to Figures 1, 2, 3, 4, 5 and other similar diagrams. While the value of the decision output may not need to be explicitly depicted on all BPMN process diagrams and on other diagrams, at least the initial few diagrams where the concepts are defined it should be depicted explicitly.

On Figure 1, in the Decision Model area, the dotted line connecting this area to the BPMN model should have a label such as "Routing Decision Output" (which the BPMN diagram implicitly assumes has a value of "ACCEPT" or "DECLINE". Similarly, diagrams 2, 3, 4, and 5 could have an "Decision Output" coming out of the Decision box and connected to it with an arrow pointing from the Decision shape to the Decision Output shape.

We do not want every decision (including sub-decisions) to have both a decision symbol (rectangle) and some symbol for the output. This would add clutter for no reason, because every decision has exactly 1 output. We discussed the possibility of having only the 'top' decision(s) show an output, but again, this is not needed and it is possible to discern the top decisions - those that are not required by any other decision.
Finally, we note that decisions have much metadata that can be used to link decisions to BPM activities, provide business motivation, etc. There is no standard notation for much of this metadata, so as not to over-constrain tools.