DMNFTF — preferedOrientation behaviour

"An instance of DecisionTable SHOULD BE represented as specified by its preferedOrientation, as defined in clause 8.2.2." You're saying that a conforming implementation is allowed to read a Decision Model written by another tool but display it with a different orientation. This is will greatly upset users, who get very attached to graphical elements being displayed exactly as they drew them. I suggest changing this to "An instance of DecisionTable SHALL be represented as specified by its preferedOrientation, as defined in clause 8.2.2."

The preferred orientation is preferred and this preference is something that vendors must maintain. However it is a PREFERRED orientation so there is not requirement that it be used to display the table.