diff --git a/org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/renderers/ProfileDrivenRenderer.java b/org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/renderers/ProfileDrivenRenderer.java
index 527099bb6..83d2f9ba9 100644
--- a/org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/renderers/ProfileDrivenRenderer.java
+++ b/org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/renderers/ProfileDrivenRenderer.java
@@ -366,137 +366,160 @@ public class ProfileDrivenRenderer extends ResourceRenderer {
       x = renderCommentsSpan(x, e);
     }
 
-    if (e instanceof StringType)
-      x.addText(((StringType) e).getValue());
-    else if (e instanceof CodeType)
-      x.addText(((CodeType) e).getValue());
-    else if (e instanceof IdType)
-      x.addText(((IdType) e).getValue());
-    else if (e instanceof Extension)
-      return;
-    else if (e instanceof InstantType)
-      x.addText(((InstantType) e).toHumanDisplay());
-    else if (e instanceof DateTimeType) {
-      renderDateTime(x, e);
-    } else if (e instanceof Base64BinaryType) {
-      Base64BinaryType b64 = (Base64BinaryType) e;
-      x.addText("(base64 data - "+(b64.getValue() == null ? "0" : b64.getValue().length)+" bytes)");
-    } else if (e instanceof org.hl7.fhir.r5.model.DateType) {
-      org.hl7.fhir.r5.model.DateType dt = ((org.hl7.fhir.r5.model.DateType) e);
-      renderDate(x, dt);
-    } else if (e instanceof Enumeration) {
-      Object ev = ((Enumeration<?>) e).getValue();
-      x.addText(ev == null ? "" : ev.toString()); // todo: look up a display name if there is one
-    } else if (e instanceof BooleanType) {
-      x.addText(((BooleanType) e).getValue().toString());
-    } else if (e instanceof CodeableConcept) {
-      renderCodeableConcept(x, (CodeableConcept) e, showCodeDetails);
-    } else if (e instanceof Coding) {
-      renderCoding(x, (Coding) e, showCodeDetails);
-    } else if (e instanceof CodeableReference) {
-      renderCodeableReference(x, (CodeableReference) e, showCodeDetails);
-    } else if (e instanceof Annotation) {
-      renderAnnotation(x, (Annotation) e);
-    } else if (e instanceof Identifier) {
-      renderIdentifier(x, (Identifier) e);
-    } else if (e instanceof org.hl7.fhir.r5.model.IntegerType) {
-      if (((org.hl7.fhir.r5.model.IntegerType) e).hasValue()) {
-        x.addText(Integer.toString(((org.hl7.fhir.r5.model.IntegerType) e).getValue()));
-      } else {
-        x.addText("??");
-      }
-    } else if (e instanceof org.hl7.fhir.r5.model.Integer64Type) {
-      if (((org.hl7.fhir.r5.model.Integer64Type) e).hasValue()) {
-        x.addText(Long.toString(((org.hl7.fhir.r5.model.Integer64Type) e).getValue()));
-      } else {
-        x.addText("??");
-      }
-    } else if (e instanceof org.hl7.fhir.r5.model.DecimalType) {
-      x.addText(((org.hl7.fhir.r5.model.DecimalType) e).getValue().toString());
-    } else if (e instanceof HumanName) {
-      renderHumanName(x, (HumanName) e);
-    } else if (e instanceof SampledData) {
-      renderSampledData(x, (SampledData) e);
-    } else if (e instanceof Address) {
-      renderAddress(x, (Address) e);
-    } else if (e instanceof ContactPoint) {
-      renderContactPoint(x, (ContactPoint) e);
-    } else if (e instanceof Expression) {
-      renderExpression(x, (Expression) e);
-    } else if (e instanceof Money) {
-      renderMoney(x, (Money) e);
-    } else if (e instanceof ContactDetail) {
-      ContactDetail cd = (ContactDetail) e;
-      if (cd.hasName()) {
-        x.tx(cd.getName()+": ");
-      }
-      boolean first = true;
-      for (ContactPoint c : cd.getTelecom()) {
-        if (first) first = false; else x.tx(",");
-        renderContactPoint(x, c);
-      }
-    } else if (e instanceof UriType) {
-      renderUri(x, (UriType) e, defn.getPath(), rcontext != null && rcontext.getResource() != null ? rcontext.getResource().getId() : null, res.getResource());
-    } else if (e instanceof Timing) {
-      renderTiming(x, (Timing) e);
-    } else if (e instanceof Range) {
-      renderRange(x, (Range) e);
-    } else if (e instanceof Quantity) {
-      renderQuantity(x, (Quantity) e, showCodeDetails);
-    } else if (e instanceof Ratio) {
-      renderQuantity(x, ((Ratio) e).getNumerator(), showCodeDetails);
-      x.tx("/");
-      renderQuantity(x, ((Ratio) e).getDenominator(), showCodeDetails);
-    } else if (e instanceof Period) {
-      Period p = (Period) e;
-      renderPeriod(x, p);
-    } else if (e instanceof Reference) {
-      Reference r = (Reference) e;
-      if (r.getReference() != null && r.getReference().contains("#")) {
-        if (containedIds.contains(r.getReference().substring(1))) {
-          x.ah(r.getReference()).tx("See "+r.getReference());
-        } else {          
-          // in this case, we render the resource in line
-          ResourceWrapper rw = null;
-          for (ResourceWrapper t : res.getContained()) {
-            if (r.getReference().substring(1).equals(t.getId())) {
-              rw = t;
-            }
-          }
-          if (rw == null) {
-            renderReference(res, x, r);
-          } else {
-            String ref = context.getResolver() != null ?context.getResolver().urlForContained(context, res.fhirType(), res.getId(), rw.fhirType(), rw.getId()) : null;
-            if (ref == null) {
-              x.an(rw.getId());
-              RenderingContext ctxtc = context.copy();
-              ctxtc.setAddGeneratedNarrativeHeader(false);
-              ctxtc.setContained(true);
-              ResourceRenderer rr = RendererFactory.factory(rw, ctxtc);
-              rr.setRcontext(new ResourceContext(rcontext, rw));
-              rr.render(parent.blockquote(), rw);
-            } else {
-              x.ah(ref).tx("See "+rw.fhirType());              
-            }
-          }
+    if (e instanceof PrimitiveType) {
+      PrimitiveType<?> p = (PrimitiveType<?>) e;
+      if (!p.hasValue()) {
+        if (p.hasExtension(ToolingExtensions.EXT_DAR)) {
+          x.tx("Absent because : ");
+          x.code().tx(p.getExtensionString(ToolingExtensions.EXT_DAR));
+        } else if (p.hasExtension(ToolingExtensions.EXT_NF)) {
+          x.tx("Null because: ");
+          x.code().tx(p.getExtensionString(ToolingExtensions.EXT_NF));        
+        } else if (p.hasExtension(ToolingExtensions.EXT_OT)) {
+          x.code().tx("Text: ");
+          x.tx(p.getExtensionString(ToolingExtensions.EXT_OT));              
+        } else if (p.hasExtension(ToolingExtensions.EXT_CQF_EXP)) {
+          x.code().tx("Value calculated by: ");
+          Expression exp = p.getExtensionByUrl(ToolingExtensions.EXT_CQF_EXP).getValueExpression();
+          x.tx(p.getExtensionString(ToolingExtensions.EXT_OT));              
+          renderExpression(x, exp);
+        } else {
+          x.addText("??");
         }
-      } else {
-        renderReference(res, x, r);
+      } else if (e instanceof StringType)
+        x.addText(((StringType) e).getValue());
+      else if (e instanceof CodeType)
+        x.addText(((CodeType) e).getValue());
+      else if (e instanceof IdType)
+        x.addText(((IdType) e).getValue());
+      else if (e instanceof InstantType)
+        x.addText(((InstantType) e).toHumanDisplay());
+      else if (e instanceof DateTimeType) {
+        renderDateTime(x, e);
+      } else if (e instanceof Base64BinaryType) {
+        Base64BinaryType b64 = (Base64BinaryType) e;
+        x.addText("(base64 data - "+(b64.getValue() == null ? "0" : b64.getValue().length)+" bytes)");
+      } else if (e instanceof org.hl7.fhir.r5.model.DateType) {
+        org.hl7.fhir.r5.model.DateType dt = ((org.hl7.fhir.r5.model.DateType) e);
+        renderDate(x, dt);
+      } else if (e instanceof Enumeration) {
+        Object ev = ((Enumeration<?>) e).getValue();
+        x.addText(ev == null ? "" : ev.toString()); // todo: look up a display name if there is one
+      } else if (e instanceof org.hl7.fhir.r5.model.IntegerType) {
+        if (((org.hl7.fhir.r5.model.IntegerType) e).hasValue()) {
+          x.addText(Integer.toString(((org.hl7.fhir.r5.model.IntegerType) e).getValue()));
+        } else {
+          x.addText("??");
+        }
+      } else if (e instanceof org.hl7.fhir.r5.model.Integer64Type) {
+        if (((org.hl7.fhir.r5.model.Integer64Type) e).hasValue()) {
+          x.addText(Long.toString(((org.hl7.fhir.r5.model.Integer64Type) e).getValue()));
+        } else {
+          x.addText("??");
+        }
+      } else if (e instanceof org.hl7.fhir.r5.model.DecimalType) {
+        x.addText(((org.hl7.fhir.r5.model.DecimalType) e).getValue().toString());
+      } else if (e instanceof UriType) {
+        renderUri(x, (UriType) e, defn.getPath(), rcontext != null && rcontext.getResource() != null ? rcontext.getResource().getId() : null, res.getResource());
+      } else if (e instanceof BooleanType) {        
+        x.addText(((BooleanType) e).getValue().toString());
+      } else { // e instanceof PrimitiveType
+        x.tx(((PrimitiveType) e).primitiveValue());
+      }
+    } else {
+      if (e instanceof Extension) {
+        return;
+      } else if (e instanceof CodeableConcept) {
+        renderCodeableConcept(x, (CodeableConcept) e, showCodeDetails);
+      } else if (e instanceof Coding) {
+        renderCoding(x, (Coding) e, showCodeDetails);
+      } else if (e instanceof CodeableReference) {
+        renderCodeableReference(x, (CodeableReference) e, showCodeDetails);
+      } else if (e instanceof Annotation) {
+        renderAnnotation(x, (Annotation) e);
+      } else if (e instanceof Identifier) {
+        renderIdentifier(x, (Identifier) e);
+      } else if (e instanceof HumanName) {
+        renderHumanName(x, (HumanName) e);
+      } else if (e instanceof SampledData) {
+        renderSampledData(x, (SampledData) e);
+      } else if (e instanceof Address) {
+        renderAddress(x, (Address) e);
+      } else if (e instanceof ContactPoint) {
+        renderContactPoint(x, (ContactPoint) e);
+      } else if (e instanceof Expression) {
+        renderExpression(x, (Expression) e);
+      } else if (e instanceof Money) {
+        renderMoney(x, (Money) e);
+      } else if (e instanceof ContactDetail) {
+        ContactDetail cd = (ContactDetail) e;
+        if (cd.hasName()) {
+          x.tx(cd.getName()+": ");
+        }
+        boolean first = true;
+        for (ContactPoint c : cd.getTelecom()) {
+          if (first) first = false; else x.tx(",");
+          renderContactPoint(x, c);
+        }
+      } else if (e instanceof Timing) {
+        renderTiming(x, (Timing) e);
+      } else if (e instanceof Range) {
+        renderRange(x, (Range) e);
+      } else if (e instanceof Quantity) {
+        renderQuantity(x, (Quantity) e, showCodeDetails);
+      } else if (e instanceof Ratio) {
+        renderQuantity(x, ((Ratio) e).getNumerator(), showCodeDetails);
+        x.tx("/");
+        renderQuantity(x, ((Ratio) e).getDenominator(), showCodeDetails);
+      } else if (e instanceof Period) {
+        Period p = (Period) e;
+        renderPeriod(x, p);
+      } else if (e instanceof Reference) {
+        Reference r = (Reference) e;
+        if (r.getReference() != null && r.getReference().contains("#")) {
+          if (containedIds.contains(r.getReference().substring(1))) {
+            x.ah(r.getReference()).tx("See "+r.getReference());
+          } else {          
+            // in this case, we render the resource in line
+            ResourceWrapper rw = null;
+            for (ResourceWrapper t : res.getContained()) {
+              if (r.getReference().substring(1).equals(t.getId())) {
+                rw = t;
+              }
+            }
+            if (rw == null) {
+              renderReference(res, x, r);
+            } else {
+              String ref = context.getResolver() != null ?context.getResolver().urlForContained(context, res.fhirType(), res.getId(), rw.fhirType(), rw.getId()) : null;
+              if (ref == null) {
+                x.an(rw.getId());
+                RenderingContext ctxtc = context.copy();
+                ctxtc.setAddGeneratedNarrativeHeader(false);
+                ctxtc.setContained(true);
+                ResourceRenderer rr = RendererFactory.factory(rw, ctxtc);
+                rr.setRcontext(new ResourceContext(rcontext, rw));
+                rr.render(parent.blockquote(), rw);
+              } else {
+                x.ah(ref).tx("See "+rw.fhirType());              
+              }
+            }
+          }
+        } else {
+          renderReference(res, x, r);
+        }
+      } else if (e instanceof Resource) {
+        return;
+      } else if (e instanceof DataRequirement) {
+        DataRequirement p  = (DataRequirement) e;
+        renderDataRequirement(x, p);
+      } else if (e instanceof UsageContext) {
+        UsageContext p  = (UsageContext) e;
+        renderUsageContext(x, p);
+      } else if (e instanceof ElementDefinition) {
+        x.tx("todo-bundle");
+      } else if (e != null && !(e instanceof Attachment) && !(e instanceof Narrative) && !(e instanceof Meta) && !(e instanceof ProductShelfLife)  && !(e instanceof RelatedArtifact)) {
+        throw new NotImplementedException("type "+e.fhirType()+" not handled. This may be due to unresolved inter-version compatibility issues");
       }
-    } else if (e instanceof Resource) {
-      return;
-    } else if (e instanceof DataRequirement) {
-      DataRequirement p  = (DataRequirement) e;
-      renderDataRequirement(x, p);
-    } else if (e instanceof UsageContext) {
-      UsageContext p  = (UsageContext) e;
-      renderUsageContext(x, p);
-    } else if (e instanceof PrimitiveType) {
-      x.tx(((PrimitiveType) e).primitiveValue());
-    } else if (e instanceof ElementDefinition) {
-      x.tx("todo-bundle");
-    } else if (e != null && !(e instanceof Attachment) && !(e instanceof Narrative) && !(e instanceof Meta) && !(e instanceof ProductShelfLife)  && !(e instanceof RelatedArtifact)) {
-      throw new NotImplementedException("type "+e.fhirType()+" not handled. This may be due to unresolved inter-version compatibility issues");
     }
   }