This resource corresponds with the Mobile Device Configuration Profiles feature.
Configuration profiles are comprised of XML data and require special considerations when working them via the API. Since the Classic API requires XML for PUT and POST operations, we must encode the configuration payload contents so the API can differentiate between the XML of the request body and the XML of the configuration profile.
This article provides more details about characters that commonly need to be encoded. Many online HTML or URL encoders are able to automate this process.
At this time, the API does not support the ability to interact with signed configuration profiles.