diff --git a/org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/conformance/profile/ProfileUtilities.java b/org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/conformance/profile/ProfileUtilities.java
index 554dc8608..6203ef67c 100644
--- a/org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/conformance/profile/ProfileUtilities.java
+++ b/org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/conformance/profile/ProfileUtilities.java
@@ -1662,6 +1662,9 @@ public class ProfileUtilities extends TranslatingUtilities {
             if (isLikelySourceURLReference(url, resourceNames, baseFilenames, localFilenames)) {
               b.append("](");
               b.append(basePath);
+              if (!Utilities.noString(basePath) && !basePath.endsWith("/")) {
+                b.append("/");
+              }
               i = i + 1;
             } else {
               b.append("](");
@@ -1740,8 +1743,11 @@ public class ProfileUtilities extends TranslatingUtilities {
         url.startsWith("loinc.html") ||
         url.startsWith("http.html") ||
         url.startsWith("references") ||
+        url.startsWith("license.html") ||
         url.startsWith("narrative.html") || 
         url.startsWith("search.html") ||
+        url.startsWith("security.html") ||
+        url.startsWith("versions.html") ||
         url.startsWith("patient-operation-match.html") ||
         (url.startsWith("extension-") && url.contains(".html")) || 
         url.startsWith("resource-definitions.html");
diff --git a/org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/elementmodel/Element.java b/org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/elementmodel/Element.java
index bd4f04a37..93f0ce092 100644
--- a/org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/elementmodel/Element.java
+++ b/org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/elementmodel/Element.java
@@ -1314,5 +1314,52 @@ public class Element extends Base {
 
     throw new Error("Unrecognised name "+name+" on "+this.name); 
   }
+
+  @Override
+  public Base copy() {
+    Element element = new Element(this);
+    this.copyValues(element);
+    return element;
+  }
+
+  @Override
+  public void copyValues(Base dst) {
+    super.copyValues(dst);
+    
+    Element dest = (Element) dst;
+    if (comments != null) {
+      dest.comments = new ArrayList<>();
+      dest.comments.addAll(comments);
+    } else {
+      dest.comments = null;
+    }
+    dest.value = value;
+    if (children != null) {
+      dest.children = new ArrayList<>();
+      dest.children.addAll(children);
+    } else {
+      dest.children = null;
+    }
+    dest.line = line;
+    dest.col = col;
+    dest.xhtml = xhtml;
+    dest.explicitType = explicitType;
+    dest.hasParentForValidator = false;
+    dest.path = path;
+    dest.messages = null;
+    dest.prohibited = prohibited;
+    dest.required = required;
+    dest.childMap = null;
+    dest.descendentCount = descendentCount;
+    dest.instanceId = instanceId;
+    dest.isNull = isNull;
+    dest.source = source;
+  }
+  
+  public Base setProperty(String name, Base value) throws FHIRException {
+    setChildValue(name, value.primitiveValue());
+    return this;
+  }
+  
   
 }
\ No newline at end of file
diff --git a/org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/model/Base.java b/org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/model/Base.java
index 3ffcab8bf..0aeba8345 100644
--- a/org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/model/Base.java
+++ b/org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/model/Base.java
@@ -420,6 +420,8 @@ public abstract class Base implements Serializable, IBase, IElement {
     return null; 
   }
 
+  public abstract Base copy();
+  
   public void copyValues(Base dst) {   
   }
 
diff --git a/org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/model/ExpressionNode.java b/org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/model/ExpressionNode.java
index 0a3ae3746..e5af0adef 100644
--- a/org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/model/ExpressionNode.java
+++ b/org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/model/ExpressionNode.java
@@ -56,7 +56,7 @@ public class ExpressionNode {
     Encode, Decode, Escape, Unescape, Trim, Split, Join, LowBoundary, HighBoundary, Precision,
     
     // Local extensions to FHIRPath
-    HtmlChecks1, HtmlChecks2, AliasAs, Alias;
+    HtmlChecks1, HtmlChecks2, AliasAs, Alias, Comparable;
 
     public static Function fromCode(String name) {
       if (name.equals("empty")) return Function.Empty;
@@ -118,6 +118,7 @@ public class ExpressionNode {
       if (name.equals("htmlChecks")) return Function.HtmlChecks1;
       if (name.equals("htmlchecks")) return Function.HtmlChecks1; // support change of care from R3
       if (name.equals("htmlChecks2")) return Function.HtmlChecks2;
+      if (name.equals("comparable")) return Function.Comparable;
       if (name.equals("encode")) return Function.Encode;
       if (name.equals("decode")) return Function.Decode;      
       if (name.equals("escape")) return Function.Escape;
@@ -227,6 +228,7 @@ public class ExpressionNode {
       case Join : return "join";
       case HtmlChecks1 : return "htmlChecks";
       case HtmlChecks2 : return "htmlChecks2";
+      case Comparable : return "comparable";
       case OfType : return "ofType";
       case Type : return "type";
       case ToInteger : return "toInteger";
diff --git a/org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/model/Tuple.java b/org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/model/Tuple.java
index ddffee042..0fff6567e 100644
--- a/org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/model/Tuple.java
+++ b/org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/model/Tuple.java
@@ -98,5 +98,12 @@ public class Tuple extends Base {
       return getProperty(name.hashCode(), name, checkValid);
   }
 
+  @Override
+  public Base copy() {
+    Tuple tuple = new Tuple();
+    copyValues(tuple);
+    return tuple;
+  }
+
 
 }
\ No newline at end of file
diff --git a/org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/utils/FHIRPathEngine.java b/org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/utils/FHIRPathEngine.java
index f8f9f1d2a..238a1e87b 100644
--- a/org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/utils/FHIRPathEngine.java
+++ b/org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/utils/FHIRPathEngine.java
@@ -147,6 +147,11 @@ public class FHIRPathEngine {
     public String primitiveValue() {
       return value;
     }
+
+    @Override
+    public Base copy() {
+      throw new Error("Not Implemented");
+    }
   }
 
   private class ClassTypeInfo extends Base {
@@ -205,6 +210,11 @@ public class FHIRPathEngine {
         return instance.fhirType();
       }
     }
+
+    @Override
+    public Base copy() {
+      throw new Error("Not Implemented");
+    }
   }
 
   public static class TypedElementDefinition {
@@ -1403,6 +1413,7 @@ public class FHIRPathEngine {
     case Join: return checkParamCount(lexer, location, exp, 1);    
     case HtmlChecks1: return checkParamCount(lexer, location, exp, 0);
     case HtmlChecks2: return checkParamCount(lexer, location, exp, 0);
+    case Comparable: return checkParamCount(lexer, location, exp, 1);
     case ToInteger: return checkParamCount(lexer, location, exp, 0);
     case ToDecimal: return checkParamCount(lexer, location, exp, 0);
     case ToString: return checkParamCount(lexer, location, exp, 0);
@@ -3335,6 +3346,8 @@ public class FHIRPathEngine {
       return new TypeDetails(CollectionStatus.SINGLETON, TypeDetails.FP_Boolean);
     case HtmlChecks2 : 
       return new TypeDetails(CollectionStatus.SINGLETON, TypeDetails.FP_Boolean);
+    case Comparable : 
+      return new TypeDetails(CollectionStatus.SINGLETON, TypeDetails.FP_Boolean);
     case Alias : 
       checkParamTypes(exp, exp.getFunction().toCode(), paramTypes, new TypeDetails(CollectionStatus.SINGLETON, TypeDetails.FP_String)); 
       return anything(CollectionStatus.SINGLETON); 
@@ -3551,7 +3564,7 @@ public class FHIRPathEngine {
   }
 
   private void checkContextContinuous(TypeDetails focus, String name, ExpressionNode expr) throws PathEngineException {
-    if (!focus.hasNoTypes() && !focus.hasType("decimal") && !focus.hasType("date") && !focus.hasType("dateTime") && !focus.hasType("time")) {
+    if (!focus.hasNoTypes() && !focus.hasType("decimal") && !focus.hasType("date") && !focus.hasType("dateTime") && !focus.hasType("time") && !focus.hasType("Quantity")) {
       throw makeException(expr, I18nConstants.FHIRPATH_CONTINUOUS_ONLY, name, focus.describe());
     }    
   }
@@ -3641,6 +3654,7 @@ public class FHIRPathEngine {
     case Alias : return funcAlias(context, focus, exp);
     case HtmlChecks1 : return funcHtmlChecks1(context, focus, exp);
     case HtmlChecks2 : return funcHtmlChecks2(context, focus, exp);
+    case Comparable : return funcComparable(context, focus, exp);
     case ToInteger : return funcToInteger(context, focus, exp);
     case ToDecimal : return funcToDecimal(context, focus, exp);
     case ToString : return funcToString(context, focus, exp);
@@ -3880,7 +3894,10 @@ public class FHIRPathEngine {
   }
 
   private List<Base> funcLowBoundary(ExecutionContext context, List<Base> focus, ExpressionNode expr) {
-    if (focus.size() != 1) {
+    if (focus.size() == 0) {
+      return makeNull();
+    }
+    if (focus.size() > 1) {
       throw makeExceptionPlural(focus.size(), expr, I18nConstants.FHIRPATH_FOCUS, "lowBoundary", focus.size());
     }
     int precision = 0;
@@ -3903,6 +3920,11 @@ public class FHIRPathEngine {
       result.add(new DateTimeType(Utilities.lowBoundaryForDate(base.primitiveValue(), precision == 0 ? 17 : precision)));
     } else if (base.hasType("time")) {
       result.add(new TimeType(Utilities.lowBoundaryForTime(base.primitiveValue(), precision == 0 ? 9 : precision)));
+    } else if (base.hasType("Quantity")) {
+      String value = getNamedValue(base, "value");
+      Base v = base.copy();
+      v.setProperty("value", new DecimalType(Utilities.lowBoundaryForDecimal(value, precision == 0 ? 8 : precision)));
+      result.add(v);
     } else {
       makeException(expr, I18nConstants.FHIRPATH_WRONG_PARAM_TYPE, "sqrt", "(focus)", base.fhirType(), "decimal or date");
     }
@@ -3910,7 +3932,10 @@ public class FHIRPathEngine {
   }
   
   private List<Base> funcHighBoundary(ExecutionContext context, List<Base> focus, ExpressionNode expr) {
-    if (focus.size() != 1) {
+    if (focus.size() == 0) {
+      return makeNull();
+    }
+    if (focus.size() > 1) {
       throw makeExceptionPlural(focus.size(), expr, I18nConstants.FHIRPATH_FOCUS, "highBoundary", focus.size());
     }
     int precision = 0;
@@ -3933,6 +3958,11 @@ public class FHIRPathEngine {
       result.add(new DateTimeType(Utilities.highBoundaryForDate(base.primitiveValue(), precision == 0 ? 17 : precision)));
     } else if (base.hasType("time")) {
       result.add(new TimeType(Utilities.highBoundaryForTime(base.primitiveValue(), precision == 0 ? 9 : precision)));
+    } else if (base.hasType("Quantity")) {
+      String value = getNamedValue(base, "value");
+      Base v = base.copy();
+      v.setProperty("value", new DecimalType(Utilities.highBoundaryForDecimal(value, precision == 0 ? 8 : precision)));
+      result.add(v);
     } else {
       makeException(expr, I18nConstants.FHIRPATH_WRONG_PARAM_TYPE, "sqrt", "(focus)", base.fhirType(), "decimal or date");
     }
@@ -4167,6 +4197,47 @@ public class FHIRPathEngine {
     return false;
   }
 
+  private List<Base> funcComparable(ExecutionContext context, List<Base> focus, ExpressionNode exp) throws FHIRException {
+    if (focus.size() != 1 || !(focus.get(0).fhirType().equals("Quantity"))) {
+      return makeBoolean(false);          
+    }
+    List<Base> nl = execute(context, focus, exp.getParameters().get(0), true);
+    if (nl.size() != 1 || !(nl.get(0).fhirType().equals("Quantity"))) {
+      return makeBoolean(false);          
+    }
+    String s1 = getNamedValue(focus.get(0), "system");
+    String u1 = getNamedValue(focus.get(0), "code");
+    String s2 = getNamedValue(nl.get(0), "system");
+    String u2 = getNamedValue(nl.get(0), "code");
+    
+    if (s1 == null || s2 == null || !s1.equals(s2)) {
+      return makeBoolean(false);                
+    }
+    if (u1 == null || u2 == null) {
+      return makeBoolean(false);                
+    }
+    if (u1.equals(u2)) {
+      return makeBoolean(true);
+    }
+    if (s1.equals("http://unitsofmeasure.org") && worker.getUcumService() != null) {
+      try {
+        return makeBoolean(worker.getUcumService().isComparable(u1, u2));
+      } catch (UcumException e) {
+        return makeBoolean(false);  
+      }  
+    } else {
+      return makeBoolean(false);  
+    }
+  }
+
+
+  private String getNamedValue(Base base, String name) {
+    Property p = base.getChildByName(name);
+    if (p.hasValues() && p.getValues().size() == 1) {
+      return p.getValues().get(0).primitiveValue();
+    }
+    return null;
+  }
 
   private boolean checkHtmlNames(XhtmlNode node) {
     if (node.getNodeType() == NodeType.Comment) {
diff --git a/org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/utils/GraphQLEngine.java b/org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/utils/GraphQLEngine.java
index e4c93f55a..741203d27 100644
--- a/org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/utils/GraphQLEngine.java
+++ b/org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/utils/GraphQLEngine.java
@@ -106,6 +106,11 @@ public class GraphQLEngine implements IGraphQLEngine {
       default: return super.getNamedProperty(_hash, _name, _checkValid);
       }
     }
+    
+    @Override
+    public Base copy() {
+      throw new Error("Not Implemented");
+    }
   }
 
   public static class SearchWrapper extends Base {
@@ -195,6 +200,11 @@ public class GraphQLEngine implements IGraphQLEngine {
       return null;
     }
 
+    @Override
+    public Base copy() {
+      throw new Error("Not Implemented");
+    }
+
   }
   
   private IWorkerContext context;