Where to find details on setting BP update XML fields?

We're setting up BP update transactions via XML and are having difficulty finding details on how to populate some of the control data in the XML structure.

Our SAP consultants contend that, beyond structural BP docs, there are no docs produced by SAP that describe requisite parameters and how they should be set - is that true?

Some of the requisites I've guessed are below. Where can I find docs on these, or at a minimum, an example of an out-of-the-box BP transaction that would be successful?

- PartnerHeader ObjectType needs to be set to "BusinessPartner"

- The PartyID and its scheme attributes need to be set appropriately

- "updateindicator" attribute for an element to be updated needs to be set to "X"

- ObjectTaskChangeIndicator element value needs to be set to "U"

Thank you!

Steve