Is the XML declaration required in custom media types?

Is the

<?xml version="1.0" encoding="utf-8"?>

require开发者_如何转开发d in custom media types?

I am developing a RESTful API and I have custom media types such as:

application/vnd.mywebsite.com.order+xml

But I am not sure if the XML declaration is required in the response or not.

Thanks.

---

XML documents SHOULD contain a declaration but it is not required. Whether you are using a custom media type or not is not really relevant.