Partial update using AIF (AX 4.0 SP2)

Hi

Trying to do partial updates to a sales order line using a custom made Axd document class. Read somewhere that this is not possible in AX 4.0 (only in AX 5.0) but also that there should be possible to tweak it to get the updates in.

Any good ideas or examples would be very appriciated.

Updateing a full record (where the message contians all fields is not very difficult, this is standrad functionality) But I need to send just one or two fileds and updat the sales order with just that. To avoid sende big XML message containt data that has not changed/You do not want to change

Br

Thomas