In Manufacturing Systems Definition, you can make changes (such as copying and pasting a work instruction from one operation to another) to the ordering of work instructions. These changes affect Work Instructions Planning functions when you next open the workbench.
If you have disrupted the linear precedence of work instructions outside of the Work Instructions Planning workbench, when you next open the system in the workbench, a warning appears:
Work Instruction reordering has been disabled due to the detection of an existing invalid sequence
You cannot use drag-and-drop reordering as long as this sequence error exists. To fix the precedence, open a workbench that gives you access to the Gantt chart, and use the Create Precedence Link command to re-establish linear precedence.
Note:
To avoid issues with copy and paste on the PPR tree, remember that you can effectively copy and paste a work instruction within Work Instructions Planning by inserting a work instruction into a catalog, and then inserting the catalogued work instruction into an operation.