What's this web service protocol? Unfamiliar XML Format

Question

I'm following a document to send a request to a web service, but I'm confused about it's protocol.

It's based on HTTP, but it's not in SOAP format nor XML-RPC.

Is it in an standard protocol format or they just implement their custom protocol? Here is a sample request:

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<ns2:WebStart xmlns:ns2="http://abc.efg/hij/" deliveryAddress="false" usecase="199" test="false" orderChannel="web" autoCapture="true" version="1.0" traceNo="123456" origin="12345678" lang="en" callback="http://anywhere/xmlresp.php"&gt;
    <Payer>
        <Identifier type="id">569852</Identifier>
    </Payer>
    <Payee>
        <Identifier type="id">7128</Identifier>
    </Payee>
    <Amount vat="0" currency="USD">10</Amount>
    <OrderID>127</OrderID>
    <ReturnUrl>http://anywhere/xmlresp.php&lt;/ReturnUrl&gt;
</ns2:WebStart>

Anyone familiar with the above xml format?

Answer 1

It can be REST = custom format.

Edit: How do you call such service? Is it based on URL and HTTP GET / POST requests? If so then it is REST. Otherwise it is some custom protocol.