The first two lines of every response contain version information. The first line details the XML version used, which, in this example, is 1.0. The first line also includes the character encoding, which, in this example, is UTF-8.

The second line of every response contains the name of the response, which is named after the operation in the request. In this example, the ItemLookup operation returns a response element named ItemLookupResponse.

The second line also contains the version of Product Advertising API used to create the response. In this example, the version number is 2006-09-13. If a version is not specified in a request, Product Advertising API uses the default version, 2005-10-05. Make sure to specify the latest version number if you want the latest Product Advertising API functionality.