An introduction to DMN can be found in Flowable DMN documentation.

BPM add-on provides an administration screen for decision table modeling.

dmn modeler

In the model editor, you can add new input and output columns, edit column variable names, types, and captions. In the input entries expressions, the == operator can be omitted. String values in input entries expressions should be wrapped in double quotes.

dmn input edit

Using the action buttons panel you can deploy the decision table to the DMN engine or save the table definition draft if you wish to continue working on it later.

dmn action buttons

The decision table result will be stored in the corresponding process variable. Properties panel of the sequence flow element in the modeler has an interface for working with decision table results.

dmn flow