This option only fits for catalogs which have an order number. Advantage: With an unique ID the mapping should automatically be created in any case.

You should be sure that the number is unique and can identify the part precisely in old and new catalog.

Catalog is reviewed / many changes / but the order numbers remained the same.

Normally all table variables are used. If this option is activated, only the variable of the order number is used. This will work without any failures, if no order numbers changed (were deleted, added) and only other variable values have been modified. Nevertheless, you should have a look on the mapping. The icons show whether there are rows, which should be checked. If the order number is built by an algorithm, problems could arise.