diff --git a/RELEASE_NOTES.md b/RELEASE_NOTES.md
index e69de29bb..c1786be61 100644
--- a/RELEASE_NOTES.md
+++ b/RELEASE_NOTES.md
@@ -0,0 +1,14 @@
+Validator:
+* Better validation of bad references (and fix NPE)
+* Rework output to be more informative and cleaner 
+* Fix bugs in validation of nested bundles 
+* Fix bug loading package with no specified version
+* fix bugs loading discovered packages on the fly
+* Validator now supports logical models in XML wkith no namespaces
+
+Other code changes:
+* Add version conversion for AllergyIntolerance (1.2 <-> 3.0 & 1.2 <-> 4.0)
+* Add version conversion for MedicationRequest
+* Fix rendering of documents 
+* fix for not rendering null values in patterns for must-support view
+
diff --git a/org.hl7.fhir.convertors/src/main/java/org/hl7/fhir/convertors/conv10_30/AllergyIntolerance10_30.java b/org.hl7.fhir.convertors/src/main/java/org/hl7/fhir/convertors/conv10_30/AllergyIntolerance10_30.java
index 0baaa0f3f..fcb2bb778 100644
--- a/org.hl7.fhir.convertors/src/main/java/org/hl7/fhir/convertors/conv10_30/AllergyIntolerance10_30.java
+++ b/org.hl7.fhir.convertors/src/main/java/org/hl7/fhir/convertors/conv10_30/AllergyIntolerance10_30.java
@@ -12,9 +12,9 @@ public class AllergyIntolerance10_30 {
         VersionConvertor_10_30.copyDomainResource(src, tgt);
         for (org.hl7.fhir.dstu2.model.Identifier identifier : src.getIdentifier()) tgt.addIdentifier(VersionConvertor_10_30.convertIdentifier(identifier));
         if (src.hasOnset())
-            tgt.setOnset(new org.hl7.fhir.dstu3.model.DateTimeType(src.getOnset()));
+            tgt.setOnset(VersionConvertor_10_30.convertDateTime(src.getOnsetElement()));
         if (src.hasRecordedDate())
-            tgt.setAssertedDate(src.getRecordedDate());
+            tgt.setAssertedDateElement(VersionConvertor_10_30.convertDateTime(src.getRecordedDateElement()));
         if (src.hasRecorder())
             tgt.setRecorder(VersionConvertor_10_30.convertReference(src.getRecorder()));
         if (src.hasPatient())
@@ -40,7 +40,7 @@ public class AllergyIntolerance10_30 {
         if (src.hasCategory())
             tgt.addCategory(org.hl7.fhir.dstu3.model.AllergyIntolerance.AllergyIntoleranceCategory.fromCode(src.getCategory().toCode()));
         if (src.hasLastOccurence())
-            tgt.setLastOccurrence(src.getLastOccurence());
+            tgt.setLastOccurrenceElement(VersionConvertor_10_30.convertDateTime(src.getLastOccurenceElement()));
         if (src.hasNote())
             tgt.addNote(VersionConvertor_10_30.convertAnnotation(src.getNote()));
         for (org.hl7.fhir.dstu2.model.AllergyIntolerance.AllergyIntoleranceReactionComponent reaction : src.getReaction())
@@ -63,9 +63,9 @@ public class AllergyIntolerance10_30 {
             ));
         for (org.hl7.fhir.dstu2.model.CodeableConcept concept : src.getManifestation()) tgt.addManifestation(VersionConvertor_10_30.convertCodeableConcept(concept));
         if (src.hasDescription())
-            src.setDescription(src.getDescription());
+            tgt.setDescriptionElement(VersionConvertor_10_30.convertString(src.getDescriptionElement()));
         if (src.hasOnset())
-            tgt.setOnset(src.getOnset());
+            tgt.setOnsetElement(VersionConvertor_10_30.convertDateTime(src.getOnsetElement()));
         if (src.hasSeverity())
             tgt.setSeverity(org.hl7.fhir.dstu3.model.AllergyIntolerance.AllergyIntoleranceSeverity.fromCode(src.getSeverity().toCode()));
         if (src.hasExposureRoute())
diff --git a/org.hl7.fhir.convertors/src/main/java/org/hl7/fhir/convertors/conv10_40/AllergyIntolerance10_40.java b/org.hl7.fhir.convertors/src/main/java/org/hl7/fhir/convertors/conv10_40/AllergyIntolerance10_40.java
index 0f9760ff9..e5c51c648 100644
--- a/org.hl7.fhir.convertors/src/main/java/org/hl7/fhir/convertors/conv10_40/AllergyIntolerance10_40.java
+++ b/org.hl7.fhir.convertors/src/main/java/org/hl7/fhir/convertors/conv10_40/AllergyIntolerance10_40.java
@@ -13,7 +13,7 @@ public class AllergyIntolerance10_40 {
         if (src.hasOnset())
             tgt.setOnset(VersionConvertor_10_40.convertType(src.getOnsetElement()));
         if (src.hasRecordedDate())
-            tgt.setRecordedDate(src.getRecordedDate());
+            tgt.setRecordedDateElement(VersionConvertor_10_40.convertDateTime(src.getRecordedDateElement()));
         if (src.hasRecorder())
             tgt.setRecorder(VersionConvertor_10_40.convertReference(src.getRecorder()));
         if (src.hasPatient())
@@ -44,8 +44,8 @@ public class AllergyIntolerance10_40 {
             tgt.setType(org.hl7.fhir.r4.model.AllergyIntolerance.AllergyIntoleranceType.fromCode(src.getType().toCode()));
         if (src.hasCategory())
             tgt.addCategory(org.hl7.fhir.r4.model.AllergyIntolerance.AllergyIntoleranceCategory.fromCode(src.getCategory().toCode()));
-        if (src.hasLastOccurence())
-            tgt.setLastOccurrence(src.getLastOccurence());
+        if (src.hasLastOccurenceElement())
+            tgt.setLastOccurrenceElement(VersionConvertor_10_40.convertDateTime(src.getLastOccurenceElement()));
         if (src.hasNote())
             tgt.addNote(VersionConvertor_10_40.convertAnnotation(src.getNote()));
         for (org.hl7.fhir.dstu2.model.AllergyIntolerance.AllergyIntoleranceReactionComponent reaction : src.getReaction())
@@ -68,9 +68,9 @@ public class AllergyIntolerance10_40 {
             ));
         for (org.hl7.fhir.dstu2.model.CodeableConcept concept : src.getManifestation()) tgt.addManifestation(VersionConvertor_10_40.convertCodeableConcept(concept));
         if (src.hasDescription())
-            src.setDescription(src.getDescription());
+            tgt.setDescriptionElement(VersionConvertor_10_40.convertString(src.getDescriptionElement()));
         if (src.hasOnset())
-            tgt.setOnset(src.getOnset());
+            tgt.setOnsetElement(VersionConvertor_10_40.convertDateTime(src.getOnsetElement()));
         if (src.hasSeverity())
             tgt.setSeverity(org.hl7.fhir.r4.model.AllergyIntolerance.AllergyIntoleranceSeverity.fromCode(src.getSeverity().toCode()));
         if (src.hasExposureRoute())
diff --git a/org.hl7.fhir.convertors/src/test/java/org/hl7/fhir/convertors/conv10_30/AllergyIntolerance10_30Test.java b/org.hl7.fhir.convertors/src/test/java/org/hl7/fhir/convertors/conv10_30/AllergyIntolerance10_30Test.java
index 920c0df9e..e2c5ab5fd 100644
--- a/org.hl7.fhir.convertors/src/test/java/org/hl7/fhir/convertors/conv10_30/AllergyIntolerance10_30Test.java
+++ b/org.hl7.fhir.convertors/src/test/java/org/hl7/fhir/convertors/conv10_30/AllergyIntolerance10_30Test.java
@@ -36,6 +36,14 @@ public class AllergyIntolerance10_30Test {
         org.hl7.fhir.dstu3.formats.JsonParser stu_parser = new org.hl7.fhir.dstu3.formats.JsonParser();
         org.hl7.fhir.dstu3.model.Resource stu_expected = stu_parser.parse(stu_exepected_input);
 
+        if (!stu_expected.equalsDeep(stu_actual)) {
+          System.out.println("Expected");
+          System.out.println(stu_parser.composeString(stu_expected));
+          System.out.println();
+          System.out.println("Actual");
+          System.out.println(stu_parser.composeString(stu_actual));
+        }
+        
         Assertions.assertTrue(stu_expected.equalsDeep(stu_actual),
     "Failed comparing\n" + stu_parser.composeString(stu_actual) + "\nand\n" + stu_parser.composeString(stu_expected)
         );
diff --git a/org.hl7.fhir.convertors/src/test/java/org/hl7/fhir/convertors/conv10_40/AllergyIntolerance10_40Test.java b/org.hl7.fhir.convertors/src/test/java/org/hl7/fhir/convertors/conv10_40/AllergyIntolerance10_40Test.java
index e1cf86214..6dc3cba82 100644
--- a/org.hl7.fhir.convertors/src/test/java/org/hl7/fhir/convertors/conv10_40/AllergyIntolerance10_40Test.java
+++ b/org.hl7.fhir.convertors/src/test/java/org/hl7/fhir/convertors/conv10_40/AllergyIntolerance10_40Test.java
@@ -36,8 +36,14 @@ public class AllergyIntolerance10_40Test {
         org.hl7.fhir.r4.formats.JsonParser r4_parser = new org.hl7.fhir.r4.formats.JsonParser();
         org.hl7.fhir.r4.model.Resource r4_expected = r4_parser.parse(r4_exepected_input);
 
-        Assertions.assertTrue(r4_expected.equalsDeep(r4_actual),
-    "Failed comparing\n" + r4_parser.composeString(r4_actual) + "\nand\n" + r4_parser.composeString(r4_expected)
+        if (!r4_expected.equalsDeep(r4_actual)) {
+          System.out.println("Expected");
+          System.out.println(r4_parser.composeString(r4_expected));
+          System.out.println();
+          System.out.println("Actual");
+          System.out.println(r4_parser.composeString(r4_actual));
+        }
+        Assertions.assertTrue(r4_expected.equalsDeep(r4_actual), "Failed comparing\n" + r4_parser.composeString(r4_actual) + "\nand\n" + r4_parser.composeString(r4_expected)
         );
     }
 }
diff --git a/org.hl7.fhir.convertors/src/test/resources/0_allergy_intolerance_10.json b/org.hl7.fhir.convertors/src/test/resources/0_allergy_intolerance_10.json
index 6289fa81f..7c008a863 100644
--- a/org.hl7.fhir.convertors/src/test/resources/0_allergy_intolerance_10.json
+++ b/org.hl7.fhir.convertors/src/test/resources/0_allergy_intolerance_10.json
@@ -1,20 +1,42 @@
-{"resourceType": "AllergyIntolerance",
-  "recordedDate": "2015-08-25T02:11:36",
-  "status": "confirmed",
-  "criticality": "CRITL",
-  "id": "TBwnNbrAqC0Qw5Ha7AFT-2AB",
-  "onset": "2012-11-07T00:00:00Z",
-  "recorder": {"display": "MOORE, NICK",
-    "reference": "https://open-ic.epic.com/Argonaut/api/FHIR/DSTU2/Practitioner/TItWfhjChtlo0pFh9nzctSQB"},
-  "patient": {"display": "Jason Argonaut",
-    "reference": "https://open-ic.epic.com/Argonaut/api/FHIR/DSTU2/Patient/Tbt3KuCY0B5PSrJvCu2j-PlK.aiHsu2xUjUM8bWpetXoB"},
-  "substance": {"text": "PENICILLIN G",
-    "coding": [{"system": "http://www.nlm.nih.gov/research/umls/rxnorm",
-      "code": "7980",
-      "display": "PENICILLIN G"},
-      {"system": "http://fdasis.nlm.nih.gov",
-        "code": "Q42T66VG0C",
-        "display": "PENICILLIN G"}]},
-  "reaction": [{"certainty": "confirmed",
-    "onset": "2012-11-07T00:00:00Z",
-    "manifestation": [{"text": "Hives"}]}]}
\ No newline at end of file
+{
+  "resourceType" : "AllergyIntolerance",
+  "recordedDate" : "2015-08-25T02:11:36",
+  "status" : "confirmed",
+  "criticality" : "CRITL",
+  "id" : "TBwnNbrAqC0Qw5Ha7AFT-2AB",
+  "onset" : "2012-11-07T00:00:00Z",
+  "recorder" : {
+    "display" : "MOORE, NICK",
+    "reference" : "https://open-ic.epic.com/Argonaut/api/FHIR/DSTU2/Practitioner/TItWfhjChtlo0pFh9nzctSQB"
+  },
+  "patient" : {
+    "display" : "Jason Argonaut",
+    "reference" : "https://open-ic.epic.com/Argonaut/api/FHIR/DSTU2/Patient/Tbt3KuCY0B5PSrJvCu2j-PlK.aiHsu2xUjUM8bWpetXoB"
+  },
+  "substance" : {
+    "text" : "PENICILLIN G",
+    "coding" : [
+      {
+        "system" : "http://www.nlm.nih.gov/research/umls/rxnorm",
+        "code" : "7980",
+        "display" : "PENICILLIN G"
+      },
+      {
+        "system" : "http://fdasis.nlm.nih.gov",
+        "code" : "Q42T66VG0C",
+        "display" : "PENICILLIN G"
+      }
+    ]
+  },
+  "reaction" : [
+    {
+      "certainty" : "confirmed",
+      "onset" : "2012-11-07T00:00:00Z",
+      "manifestation" : [
+        {
+          "text" : "Hives"
+        }
+      ]
+    }
+  ]
+}
diff --git a/org.hl7.fhir.convertors/src/test/resources/0_allergy_intolerance_30.json b/org.hl7.fhir.convertors/src/test/resources/0_allergy_intolerance_30.json
index b163ced15..be78790a9 100644
--- a/org.hl7.fhir.convertors/src/test/resources/0_allergy_intolerance_30.json
+++ b/org.hl7.fhir.convertors/src/test/resources/0_allergy_intolerance_30.json
@@ -1,22 +1,48 @@
-{"resourceType": "AllergyIntolerance",
-  "id": "TBwnNbrAqC0Qw5Ha7AFT-2AB",
-  "clinicalStatus": "active",
-  "verificationStatus": "confirmed",
-  "criticality": "low",
-  "code": {"coding": [{"system": "http://www.nlm.nih.gov/research/umls/rxnorm",
-    "code": "7980",
-    "display": "PENICILLIN G"},
-    {"system": "http://fdasis.nlm.nih.gov",
-      "code": "Q42T66VG0C",
-      "display": "PENICILLIN G"}],
-    "text": "PENICILLIN G"},
-  "patient": {"reference": "https://open-ic.epic.com/Argonaut/api/FHIR/DSTU2/Patient/Tbt3KuCY0B5PSrJvCu2j-PlK.aiHsu2xUjUM8bWpetXoB",
-    "display": "Jason Argonaut"},
-  "onsetDateTime": "2012-11-07T00:00:00",
-  "assertedDate": "2015-08-25T02:11:36",
-  "recorder": {"reference": "https://open-ic.epic.com/Argonaut/api/FHIR/DSTU2/Practitioner/TItWfhjChtlo0pFh9nzctSQB",
-    "display": "MOORE, NICK"},
-  "reaction": [{"extension": [{"url": "http://hl7.org/fhir/AllergyIntolerance-r2-certainty",
-    "valueString": "confirmed"}],
-    "manifestation": [{"text": "Hives"}],
-    "onset": "2012-11-07T00:00:00"}]}
+{
+  "resourceType" : "AllergyIntolerance",
+  "id" : "TBwnNbrAqC0Qw5Ha7AFT-2AB",
+  "clinicalStatus" : "active",
+  "verificationStatus" : "confirmed",
+  "criticality" : "low",
+  "code" : {
+    "coding" : [
+      {
+        "system" : "http://www.nlm.nih.gov/research/umls/rxnorm",
+        "code" : "7980",
+        "display" : "PENICILLIN G"
+      },
+      {
+        "system" : "http://fdasis.nlm.nih.gov",
+        "code" : "Q42T66VG0C",
+        "display" : "PENICILLIN G"
+      }
+    ],
+    "text" : "PENICILLIN G"
+  },
+  "patient" : {
+    "reference" : "https://open-ic.epic.com/Argonaut/api/FHIR/DSTU2/Patient/Tbt3KuCY0B5PSrJvCu2j-PlK.aiHsu2xUjUM8bWpetXoB",
+    "display" : "Jason Argonaut"
+  },
+  "onsetDateTime" : "2012-11-07T00:00:00Z",
+  "assertedDate" : "2015-08-25T02:11:36",
+  "recorder" : {
+    "reference" : "https://open-ic.epic.com/Argonaut/api/FHIR/DSTU2/Practitioner/TItWfhjChtlo0pFh9nzctSQB",
+    "display" : "MOORE, NICK"
+  },
+  "reaction" : [
+    {
+      "extension" : [
+        {
+          "url" : "http://hl7.org/fhir/AllergyIntolerance-r2-certainty",
+          "valueString" : "confirmed"
+        }
+      ],
+      "manifestation" : [
+        {
+          "text" : "Hives"
+        }
+      ],
+      "onset" : "2012-11-07T00:00:00Z"
+    }
+  ]
+}
diff --git a/org.hl7.fhir.convertors/src/test/resources/0_allergy_intolerance_40.json b/org.hl7.fhir.convertors/src/test/resources/0_allergy_intolerance_40.json
index 74030f0db..e02782189 100644
--- a/org.hl7.fhir.convertors/src/test/resources/0_allergy_intolerance_40.json
+++ b/org.hl7.fhir.convertors/src/test/resources/0_allergy_intolerance_40.json
@@ -1,23 +1,61 @@
-{"resourceType": "AllergyIntolerance",
-  "clinicalStatus": {"coding": [{"system": "http://terminology.hl7.org/CodeSystem/allergyintolerance-clinical",
-    "code": "confirmed"}]},
-  "verificationStatus": {"coding": [{"system": "http://terminology.hl7.org/CodeSystem/allergyintolerance-verification",
-    "code": "confirmed"}]},
-  "criticality": "low",
-  "code": {"coding": [{"system": "http://www.nlm.nih.gov/research/umls/rxnorm",
-    "code": "7980",
-    "display": "PENICILLIN G"},
-    {"system": "http://fdasis.nlm.nih.gov",
-      "code": "Q42T66VG0C",
-      "display": "PENICILLIN G"}],
-    "text": "PENICILLIN G"},
-  "patient": {"reference": "https://open-ic.epic.com/Argonaut/api/FHIR/DSTU2/Patient/Tbt3KuCY0B5PSrJvCu2j-PlK.aiHsu2xUjUM8bWpetXoB",
-    "display": "Jason Argonaut"},
-  "onsetDateTime": "2012-11-07T00:00:00Z",
-  "recordedDate": "2015-08-25T02:11:36",
-  "recorder": {"reference": "https://open-ic.epic.com/Argonaut/api/FHIR/DSTU2/Practitioner/TItWfhjChtlo0pFh9nzctSQB",
-    "display": "MOORE, NICK"},
-  "reaction": [{"extension": [{"url": "http://hl7.org/fhir/AllergyIntolerance-r2-certainty",
-    "valueString": "confirmed"}],
-    "manifestation": [{"text": "Hives"}],
-    "onset": "2012-11-07T00:00:00"}]}
\ No newline at end of file
+{
+  "resourceType" : "AllergyIntolerance",
+  "clinicalStatus" : {
+    "coding" : [
+      {
+        "system" : "http://terminology.hl7.org/CodeSystem/allergyintolerance-clinical",
+        "code" : "confirmed"
+      }
+    ]
+  },
+  "verificationStatus" : {
+    "coding" : [
+      {
+        "system" : "http://terminology.hl7.org/CodeSystem/allergyintolerance-verification",
+        "code" : "confirmed"
+      }
+    ]
+  },
+  "criticality" : "low",
+  "code" : {
+    "coding" : [
+      {
+        "system" : "http://www.nlm.nih.gov/research/umls/rxnorm",
+        "code" : "7980",
+        "display" : "PENICILLIN G"
+      },
+      {
+        "system" : "http://fdasis.nlm.nih.gov",
+        "code" : "Q42T66VG0C",
+        "display" : "PENICILLIN G"
+      }
+    ],
+    "text" : "PENICILLIN G"
+  },
+  "patient" : {
+    "reference" : "https://open-ic.epic.com/Argonaut/api/FHIR/DSTU2/Patient/Tbt3KuCY0B5PSrJvCu2j-PlK.aiHsu2xUjUM8bWpetXoB",
+    "display" : "Jason Argonaut"
+  },
+  "onsetDateTime" : "2012-11-07T00:00:00Z",
+  "recordedDate" : "2015-08-25T02:11:36",
+  "recorder" : {
+    "reference" : "https://open-ic.epic.com/Argonaut/api/FHIR/DSTU2/Practitioner/TItWfhjChtlo0pFh9nzctSQB",
+    "display" : "MOORE, NICK"
+  },
+  "reaction" : [
+    {
+      "extension" : [
+        {
+          "url" : "http://hl7.org/fhir/AllergyIntolerance-r2-certainty",
+          "valueString" : "confirmed"
+        }
+      ],
+      "manifestation" : [
+        {
+          "text" : "Hives"
+        }
+      ],
+      "onset" : "2012-11-07T00:00:00Z"
+    }
+  ]
+}
diff --git a/org.hl7.fhir.convertors/src/test/resources/1_allergy_intolerance_30.json b/org.hl7.fhir.convertors/src/test/resources/1_allergy_intolerance_30.json
index 36324bff6..0e8ebd1fe 100644
--- a/org.hl7.fhir.convertors/src/test/resources/1_allergy_intolerance_30.json
+++ b/org.hl7.fhir.convertors/src/test/resources/1_allergy_intolerance_30.json
@@ -1,22 +1,48 @@
-{"resourceType": "AllergyIntolerance",
-  "id": "TKebKfLXzu6Sp.LY-IpvpmQB",
-  "clinicalStatus": "active",
-  "verificationStatus": "confirmed",
-  "criticality": "high",
-  "code": {"coding": [{"system": "http://www.nlm.nih.gov/research/umls/rxnorm",
-    "code": "892484",
-    "display": "STRAWBERRY"},
-    {"system": "http://fdasis.nlm.nih.gov",
-      "code": "4J2TY8Y81V",
-      "display": "STRAWBERRY"}],
-    "text": "STRAWBERRY"},
-  "patient": {"reference": "https://open-ic.epic.com/Argonaut/api/FHIR/DSTU2/Patient/Tbt3KuCY0B5PSrJvCu2j-PlK.aiHsu2xUjUM8bWpetXoB",
-    "display": "Jason Argonaut"},
-  "onsetDateTime": "2014-03-07T00:00:00",
-  "assertedDate": "2015-11-07T22:56:34",
-  "recorder": {"reference": "https://open-ic.epic.com/Argonaut/api/FHIR/DSTU2/Practitioner/TItWfhjChtlo0pFh9nzctSQB",
-    "display": "MOORE, NICK"},
-  "reaction": [{"extension": [{"url": "http://hl7.org/fhir/AllergyIntolerance-r2-certainty",
-    "valueString": "confirmed"}],
-    "manifestation": [{"text": "Anaphylaxis"}],
-    "onset": "2014-03-07T00:00:00"}]}
\ No newline at end of file
+{
+  "resourceType" : "AllergyIntolerance",
+  "id" : "TKebKfLXzu6Sp.LY-IpvpmQB",
+  "clinicalStatus" : "active",
+  "verificationStatus" : "confirmed",
+  "criticality" : "high",
+  "code" : {
+    "coding" : [
+      {
+        "system" : "http://www.nlm.nih.gov/research/umls/rxnorm",
+        "code" : "892484",
+        "display" : "STRAWBERRY"
+      },
+      {
+        "system" : "http://fdasis.nlm.nih.gov",
+        "code" : "4J2TY8Y81V",
+        "display" : "STRAWBERRY"
+      }
+    ],
+    "text" : "STRAWBERRY"
+  },
+  "patient" : {
+    "reference" : "https://open-ic.epic.com/Argonaut/api/FHIR/DSTU2/Patient/Tbt3KuCY0B5PSrJvCu2j-PlK.aiHsu2xUjUM8bWpetXoB",
+    "display" : "Jason Argonaut"
+  },
+  "onsetDateTime" : "2014-03-07T00:00:00Z",
+  "assertedDate" : "2015-11-07T22:56:34",
+  "recorder" : {
+    "reference" : "https://open-ic.epic.com/Argonaut/api/FHIR/DSTU2/Practitioner/TItWfhjChtlo0pFh9nzctSQB",
+    "display" : "MOORE, NICK"
+  },
+  "reaction" : [
+    {
+      "extension" : [
+        {
+          "url" : "http://hl7.org/fhir/AllergyIntolerance-r2-certainty",
+          "valueString" : "confirmed"
+        }
+      ],
+      "manifestation" : [
+        {
+          "text" : "Anaphylaxis"
+        }
+      ],
+      "onset" : "2014-03-07T00:00:00Z"
+    }
+  ]
+}
diff --git a/org.hl7.fhir.convertors/src/test/resources/1_allergy_intolerance_40.json b/org.hl7.fhir.convertors/src/test/resources/1_allergy_intolerance_40.json
index cbb724f7d..a38da25a8 100644
--- a/org.hl7.fhir.convertors/src/test/resources/1_allergy_intolerance_40.json
+++ b/org.hl7.fhir.convertors/src/test/resources/1_allergy_intolerance_40.json
@@ -1,23 +1,61 @@
-{"resourceType": "AllergyIntolerance",
-  "clinicalStatus": {"coding": [{"system": "http://terminology.hl7.org/CodeSystem/allergyintolerance-clinical",
-    "code": "confirmed"}]},
-  "verificationStatus": {"coding": [{"system": "http://terminology.hl7.org/CodeSystem/allergyintolerance-verification",
-    "code": "confirmed"}]},
-  "criticality": "high",
-  "code": {"coding": [{"system": "http://www.nlm.nih.gov/research/umls/rxnorm",
-    "code": "892484",
-    "display": "STRAWBERRY"},
-    {"system": "http://fdasis.nlm.nih.gov",
-      "code": "4J2TY8Y81V",
-      "display": "STRAWBERRY"}],
-    "text": "STRAWBERRY"},
-  "patient": {"reference": "https://open-ic.epic.com/Argonaut/api/FHIR/DSTU2/Patient/Tbt3KuCY0B5PSrJvCu2j-PlK.aiHsu2xUjUM8bWpetXoB",
-    "display": "Jason Argonaut"},
-  "onsetDateTime": "2014-03-07T00:00:00Z",
-  "recordedDate": "2015-11-07T22:56:34",
-  "recorder": {"reference": "https://open-ic.epic.com/Argonaut/api/FHIR/DSTU2/Practitioner/TItWfhjChtlo0pFh9nzctSQB",
-    "display": "MOORE, NICK"},
-  "reaction": [{"extension": [{"url": "http://hl7.org/fhir/AllergyIntolerance-r2-certainty",
-    "valueString": "confirmed"}],
-    "manifestation": [{"text": "Anaphylaxis"}],
-    "onset": "2014-03-07T00:00:00"}]}
+{
+  "resourceType" : "AllergyIntolerance",
+  "clinicalStatus" : {
+    "coding" : [
+      {
+        "system" : "http://terminology.hl7.org/CodeSystem/allergyintolerance-clinical",
+        "code" : "confirmed"
+      }
+    ]
+  },
+  "verificationStatus" : {
+    "coding" : [
+      {
+        "system" : "http://terminology.hl7.org/CodeSystem/allergyintolerance-verification",
+        "code" : "confirmed"
+      }
+    ]
+  },
+  "criticality" : "high",
+  "code" : {
+    "coding" : [
+      {
+        "system" : "http://www.nlm.nih.gov/research/umls/rxnorm",
+        "code" : "892484",
+        "display" : "STRAWBERRY"
+      },
+      {
+        "system" : "http://fdasis.nlm.nih.gov",
+        "code" : "4J2TY8Y81V",
+        "display" : "STRAWBERRY"
+      }
+    ],
+    "text" : "STRAWBERRY"
+  },
+  "patient" : {
+    "reference" : "https://open-ic.epic.com/Argonaut/api/FHIR/DSTU2/Patient/Tbt3KuCY0B5PSrJvCu2j-PlK.aiHsu2xUjUM8bWpetXoB",
+    "display" : "Jason Argonaut"
+  },
+  "onsetDateTime" : "2014-03-07T00:00:00Z",
+  "recordedDate" : "2015-11-07T22:56:34",
+  "recorder" : {
+    "reference" : "https://open-ic.epic.com/Argonaut/api/FHIR/DSTU2/Practitioner/TItWfhjChtlo0pFh9nzctSQB",
+    "display" : "MOORE, NICK"
+  },
+  "reaction" : [
+    {
+      "extension" : [
+        {
+          "url" : "http://hl7.org/fhir/AllergyIntolerance-r2-certainty",
+          "valueString" : "confirmed"
+        }
+      ],
+      "manifestation" : [
+        {
+          "text" : "Anaphylaxis"
+        }
+      ],
+      "onset" : "2014-03-07T00:00:00Z"
+    }
+  ]
+}
diff --git a/org.hl7.fhir.utilities/src/main/java/org/hl7/fhir/utilities/i18n/I18nConstants.java b/org.hl7.fhir.utilities/src/main/java/org/hl7/fhir/utilities/i18n/I18nConstants.java
index 4e4fbecce..d258606dc 100644
--- a/org.hl7.fhir.utilities/src/main/java/org/hl7/fhir/utilities/i18n/I18nConstants.java
+++ b/org.hl7.fhir.utilities/src/main/java/org/hl7/fhir/utilities/i18n/I18nConstants.java
@@ -331,6 +331,7 @@ public class I18nConstants {
   public static final String REFERENCE_REF_NOTFOUND_BUNDLE = "Reference_REF_NotFound_Bundle";
   public static final String REFERENCE_REF_NOTYPE = "Reference_REF_NoType";
   public static final String REFERENCE_REF_RESOURCETYPE = "Reference_REF_ResourceType";
+  public static final String REFERENCE_REF_SUSPICIOUS = "REFERENCE_REF_SUSPICIOUS";
   public static final String REFERENCE_REF_WRONGTARGET = "Reference_REF_WrongTarget";
   public static final String REFERENCE_TO__CANNOT_BE_RESOLVED = "reference_to__cannot_be_resolved";
   public static final String REFERENCE__REFERS_TO_A__NOT_A_VALUESET = "Reference__refers_to_a__not_a_ValueSet";
diff --git a/org.hl7.fhir.utilities/src/main/resources/Messages.properties b/org.hl7.fhir.utilities/src/main/resources/Messages.properties
index 481342e10..a72555b61 100644
--- a/org.hl7.fhir.utilities/src/main/resources/Messages.properties
+++ b/org.hl7.fhir.utilities/src/main/resources/Messages.properties
@@ -604,3 +604,4 @@ FHIRPATH_BAD_DATE = Unable to parse Date {0}
 FHIRPATH_NUMERICAL_ONLY = Error evaluating FHIRPath expression: The function {0} can only be used on integer, decimal or Quantity but found {1}
 FHIRPATH_DECIMAL_ONLY = Error evaluating FHIRPath expression: The function {0} can only be used on a decimal but found {1}
 FHIRPATH_FOCUS_PLURAL = Error evaluating FHIRPath expression: focus for {0} has more than one value
+REFERENCE_REF_SUSPICIOUS = The syntax of the reference ''{0}'' looks incorrect, and it should be checked
diff --git a/org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/instance/InstanceValidator.java b/org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/instance/InstanceValidator.java
index 48179bc5e..517b06b11 100644
--- a/org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/instance/InstanceValidator.java
+++ b/org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/instance/InstanceValidator.java
@@ -2398,6 +2398,7 @@ public class InstanceValidator extends BaseValidator implements IResourceValidat
       // special known URLs that can't be validated but are known to be valid
       return;
     }
+    warning(errors, IssueType.STRUCTURE, element.line(), element.col(), path, !isSuspiciousReference(ref), I18nConstants.REFERENCE_REF_SUSPICIOUS, ref);      
 
     ResolvedReference we = localResolve(ref, stack, errors, path, (Element) hostContext.getAppContext(), element);
     String refType;
@@ -2439,10 +2440,11 @@ public class InstanceValidator extends BaseValidator implements IResourceValidat
     }
 
     String ft;
-    if (we != null)
+    if (we != null) {
       ft = we.getType();
-    else
+    } else {
       ft = tryParse(ref);
+    }
 
     if (reference.hasType()) { // R4 onwards...
       // the type has to match the specified
@@ -2596,6 +2598,20 @@ public class InstanceValidator extends BaseValidator implements IResourceValidat
     }
   }
 
+  private boolean isSuspiciousReference(String url) {
+    if (!assumeValidRestReferences || url == null || Utilities.isAbsoluteUrl(url)) {
+      return false;
+    }
+    String[] parts = url.split("\\/");
+    if (parts.length == 2 && context.getResourceNames().contains(parts[0]) && Utilities.isValidId(parts[1])) {
+      return false;
+    }
+    if (parts.length == 4 && context.getResourceNames().contains(parts[0]) && Utilities.isValidId(parts[1]) && "_history".equals(parts[2]) && Utilities.isValidId(parts[3])) {
+      return false;
+    }
+    return true;
+  }
+
   private String asListByUrl(Collection<StructureDefinition> list) {
     CommaSeparatedStringBuilder b = new CommaSeparatedStringBuilder();
     for (StructureDefinition sd : list) {
@@ -4842,7 +4858,7 @@ public class InstanceValidator extends BaseValidator implements IResourceValidat
       case 2:
         return checkResourceType(parts[0]);
       default:
-        if (parts[parts.length - 2].equals("_history"))
+        if (parts[parts.length - 2].equals("_history") && parts.length >= 4)
           return checkResourceType(parts[parts.length - 4]);
         else
           return checkResourceType(parts[parts.length - 2]);