I'm getting the impression that DNG is regulating OSLC provider link resource types. 

One reason is the OSLC provider doesn't always show up as an option in the "Create Link" pop up window.  For example, if the link type is "Satisfies" the OSLC-CM provider is not an option.  But it is an option if the link type is "Affected By".  This doesn't make sense because I can select the option to create a "Web" link in the UI for almost every link type.

Another issue is I have a OSLC client that creates links in DNG and it works fine every time regardless of the link type.  The HTTP status is always 200 after I update the resource.  The problem is when you go to the DNG UI and look for the link and it's not there but for some link types like "Elaborated By" the link is there.  Why would DNG send back a 200 if the link isn't actually created?  Or maybe it does get created in the DNG DB but the UI filters it out.  Who knows?

Finally, while trouble shooting another issue I came across the JS code below where it appears DNG can only handle or expects certain OSLC spec types...

_getResourceElement:function(_52,_53,_54,_55){
var _56=null;
if(_52!=null){
var _57=null;
switch(_54){
case _3.SYSTEM_LINK_TYPE_IMPLEMENTED_BY:
case _3.SYSTEM_LINK_TYPE_TRACKED_BY:
case _3.SYSTEM_LINK_TYPE_AFFECTED_BY:
if(_55){
_57="http://open-services.net/ns/cm-x#Plan";
}else{
_57="http://open-services.net/ns/cm#ChangeRequest";
}
break;
case _3.SYSTEM_LINK_TYPE_VALIDATED_BY:
_57="http://open-services.net/ns/qm#";
_57+=_55?"TestPlan":"TestCase";
break;
case _3.SYSTEM_LINK_TYPE_DERIVES:
case _3.SYSTEM_LINK_TYPE_SATISFY:
case _3.SYSTEM_LINK_TYPE_TRACE:
case _3.SYSTEM_LINK_TYPE_REFINE:
_57="http://open-services.net/ns/am#Resource";
break;
case _3.SYSTEM_LINK_TYPE_REFERENCES:
_57="http://open-services.net/ns/rm#Requirement";
break;
}