...
As noted above, as new namespaces are used for the first time, those namespaces will be bound permanently to particular prefixes. Currently, if the first use of a particular namespace should occur in RDF that is POSTed or PUT to the repository without including a specific prefix binding supplied in the submitted graph, Fedora will bind the new namespace to a system-generated namespace in the form "ns00x". While this behavior is not incorrect, it is inconvenient, and not necessarily user friendly for human interaction with the repository.
Suggestion
In order to establish user-defined mappings between namespace prefixes and their namespaces, it is necessary that the first time a given namespace is used in Fedora, it have the desired namespace prefix defined in the document of that request.