Parse successful
<?xml version="1.0" encoding="ISO-8859-1"?>
<Dataset xmlns="http://xml.opendap.org/ns/DAP/4.0#" xml:base="file:dap4/test_simple_4.xml" dapVersion="4.0" dmrVersion="1.0" name="test_simple_4">
    <Int32 name="x">
        <Attribute name="long_name" type="String">
            <Value>x_axis_value</Value>
        </Attribute>
    </Int32>
</Dataset>

<?xml version="1.0" encoding="ISO-8859-1"?>
<Dataset xmlns="http://xml.opendap.org/ns/DAP/4.0#" xml:base="file:dap4/test_simple_4.xml" dapVersion="4.0" dmrVersion="1.0" name="test_simple_4">
    <Int32 name="x">
        <Attribute name="long_name" type="String">
            <Value>x_axis_value</Value>
        </Attribute>
    </Int32>
</Dataset>

The data:
{ 123456789 }