I often see requests for samples of XML messages, for example, a sample message containing query criteria. There are a few resources available to help you format inbound AIF messages.
AIF Samples - There are AIF samples available on PartnerSource (this requires that you have access to PartnerSource). If you extract the zip file, under the Gateway\XML folder you'll find sample AIF messages, one for each action available. These samples use the scenario of exchanging sales order data, so, for example, readSalesOrder.xml contains the format for an inbound message containing an EntityKey element to return a sales order.
XSD Files - If you're running Microsoft Dynamics AX 4.0, there are XSD files that ship with the product. Use these XSDs to validate non-document-specific elements in a message such as the header, query criteria, entity key, and so on. These files are located at <InstallationDirectory>Microsoft Dynamics AX\40\Axapta Application\Share\Include. The files are:
You'll need some software that will allow you to validate your XML against the XSD files but there are plenty of options out there.