Paymo service uses the REST XML response format. It's a simple XML block.
The available response formats are:
To return the response in REST XML format, send a parameter format in the request with a value of xml. If method argument is not specified, it defaults to xml.
For the JSON response format, send the parameter format with a value of json.
A response in XML format returns this:
<?xml version="1.0" encoding="utf-8" ?>
<response status="ok">
[xml-payload-here]
</response>
If an error occurs, the following is returned:
<?xml version="1.0" encoding="utf-8" ?>
<response status="error">
<error code="[error-code]" message="[error-message]" />
</response>
For the exact format of the response, see the "Example Response" section from the documentation page of the specific API method.