One question that often comes up is why the CCD, or other specifications based upon it only specify what kind of advance directive exists and where to find it, and do not what the content further. But providers do want to know what's in these things so that they can act appropriately.
When this topic was discussed (in three different venues I might add), three years ago, there was a problems identified with classifying details of an advance directive. The classification of advance directives depends upon the legal jurisdiction where it is interpreted. To say any more than "an advance directive with respect to resuscitation status" exists could have patient safety and legal implications that could not be resolved using any existing controlled vocabulary, and it still cannot today.
Many advance directives are are legal documents, and the content of them is often unconstrained. It could say just about anything you want to in words, and that even when the document has same name (a classification such as a DNR Order), they may have different meanings depending upon the state in which you live or are recieving care.
As a consequence, the CCD and specifications from IHE and HITSP which derive from it do not specify what appears within an advance directive. The advice given to the developers of CCD, based on policies and procedures in force at many institutions, was to alert the provider of the existence of these documents, and to provide references to where they could obtain the content, so as to comply with what the advance directive itself says, and not based on a shorthand assessment and classification of its content.