The Client sends to the Yarn Producer an Order Change any time he must modify some conditions of his previous Order (eg. to cancel items not delivered in time) or amend errors (eg. invalid prices).

Basic function of the message is to replace an invalid Order with a valid Order, amending:

- suppliable quantities

- dates and places of delivery

- prices

The Order Change can show a number of lines different from the related Purchase Order, when variations/cancellations have occurred so as to create the splitting of an Order Line.

However the sum of the quantities of the lines in the Order Change (confirmed + varied + cancelled) must always not less than the sum of the quantities in the original Order.
When the quantity is change the original line must be splitted and the confimed amount and canceled amount should be explicited through the 'act' flag.