diff --git a/Xbim.BCF/MarkupXMLFile.cs b/Xbim.BCF/MarkupXMLFile.cs
index 2bc8fb3..3aeaaa5 100644
--- a/Xbim.BCF/MarkupXMLFile.cs
+++ b/Xbim.BCF/MarkupXMLFile.cs
@@ -27,8 +27,8 @@ public MarkupXMLFile(XDocument xdoc)
         {
             Comments = new List<BCFComment>();
             Viewpoints = new List<BCFViewpoint>();
-
-            Header = new BCFHeader(xdoc.Root.Element("Header"));
+            if (xdoc.Root.Element("Header") != null)
+                Header = new BCFHeader(xdoc.Root.Element("Header"));
             Topic = new BCFTopic(xdoc.Root.Element("Topic"));
             foreach (var comment in (xdoc.Root.Elements("Comment")))
             {
diff --git a/Xbim.BCF/VisualizationXMLFile.cs b/Xbim.BCF/VisualizationXMLFile.cs
index d3644a9..bfed31a 100644
--- a/Xbim.BCF/VisualizationXMLFile.cs
+++ b/Xbim.BCF/VisualizationXMLFile.cs
@@ -19,7 +19,8 @@ public Guid Guid
             {
                 if (value == null || value == System.Guid.Empty)
                 {
-                    throw new ArgumentException(this.GetType().Name + " - Guid attribute is mandatory and must contain a valid Guid value");
+                    // don't stop if Guid is missing
+                    // throw new ArgumentException(this.GetType().Name + " - Guid attribute is mandatory and must contain a valid Guid value");
                 }
                 else
                 {
diff --git a/Xbim.BCF/XMLNodes/BCFComponents.cs b/Xbim.BCF/XMLNodes/BCFComponents.cs
index ca89947..a9199b5 100644
--- a/Xbim.BCF/XMLNodes/BCFComponents.cs
+++ b/Xbim.BCF/XMLNodes/BCFComponents.cs
@@ -32,7 +32,8 @@ public BCFComponentVisibility Visibility
             {
                 if (ReferenceEquals(value, null))
                 {
-                    throw new ArgumentException(this.GetType().Name + " - Visibility is mandatory");
+                    // don't stop if Visibility is missing
+                    // throw new ArgumentException(this.GetType().Name + " - Visibility is mandatory");
                 }
                 else
                 {
diff --git a/Xbim.BCF/XMLNodes/BCFPerspectiveCamera.cs b/Xbim.BCF/XMLNodes/BCFPerspectiveCamera.cs
index 4620118..174336c 100644
--- a/Xbim.BCF/XMLNodes/BCFPerspectiveCamera.cs
+++ b/Xbim.BCF/XMLNodes/BCFPerspectiveCamera.cs
@@ -71,9 +71,9 @@ public double FieldOfView
             get { return _fieldOfView; }
             set
             {
-                if (value == double.NaN || value < 45 || value > 60)
+                if (value == double.NaN || value < 0 || value > 360)
                 {
-                    throw new ArgumentException(this.GetType().Name + " - FieldOfView - must be a valid 64-bit floating-point value between 45 and 60");
+                    throw new ArgumentException(this.GetType().Name + " - FieldOfView - must be a valid 64-bit floating-point value between 0 and 360");
                 }
                 else
                 {
diff --git a/Xbim.BCF/XMLNodes/BCFTopic.cs b/Xbim.BCF/XMLNodes/BCFTopic.cs
index 3f9bf4a..68fc76d 100644
--- a/Xbim.BCF/XMLNodes/BCFTopic.cs
+++ b/Xbim.BCF/XMLNodes/BCFTopic.cs
@@ -93,11 +93,20 @@ public bool ShouldSerializeIndex()
         {
             return Index != null;
         }
+        /// <summary>
+        /// Topic Labels. Tags for grouping Topics. The list of possible values are defined in the extension schema.
+        /// </summary>
+        [XmlElement(Order = 6)]
+        public String Labels { get; set; }
+        public bool ShouldSerializeLabels()
+        {
+            return !string.IsNullOrEmpty(Labels);
+        }
         private DateTime? _creationDate;
         /// <summary>
         /// Date when the topic was created
         /// </summary>
-        [XmlElement(Order = 6)]
+        [XmlElement(Order = 7)]
         public DateTime? CreationDate
         {
             get { return _creationDate; }
@@ -117,7 +126,7 @@ public DateTime? CreationDate
         /// <summary>
         /// User who created the topic
         /// </summary>
-        [XmlElement(Order = 7)]
+        [XmlElement(Order = 8)]
         public String CreationAuthor
         {
             get { return _creationAuthor; }
@@ -125,7 +134,8 @@ public String CreationAuthor
             {
                 if (String.IsNullOrEmpty(value))
                 {
-                    throw new ArgumentException(this.GetType().Name + " - CreationAuthor is mandatory");
+                    // don't stop if CreationAuthor is missing
+                    // throw new ArgumentException(this.GetType().Name + " - CreationAuthor is mandatory");
                 }
                 else
                 {
@@ -135,7 +145,7 @@ public String CreationAuthor
         }
         /// Date when the topic was last modified
         /// </summary>
-        [XmlElement(Order = 8)]
+        [XmlElement(Order = 9)]
         public DateTime? ModifiedDate { get; set; }
         public bool ShouldSerializeModifiedDate()
         {
@@ -144,7 +154,7 @@ public bool ShouldSerializeModifiedDate()
         /// <summary>
         /// User who modified the topic
         /// </summary>
-        [XmlElement(Order = 9)]
+        [XmlElement(Order = 10)]
         public String ModifiedAuthor { get; set; }
         public bool ShouldSerializeModifiedAuthor()
         {
@@ -153,7 +163,7 @@ public bool ShouldSerializeModifiedAuthor()
         /// <summary>
         /// Due date
         /// </summary>
-        [XmlElement(Order = 10)]
+        [XmlElement(Order = 11)]
         public DateTime? DueDate { get; set; }
         public bool ShouldSerializeDueDate()
         {
@@ -162,7 +172,7 @@ public bool ShouldSerializeDueDate()
         /// <summary>
         /// The user to whom this topic is assigned to
         /// </summary>
-        [XmlElement(Order = 11)]
+        [XmlElement(Order = 12)]
         public String AssignedTo { get; set; }
         public bool ShouldSerializeAssignedTo()
         {
@@ -171,7 +181,7 @@ public bool ShouldSerializeAssignedTo()
         /// <summary>
         /// Stage
         /// </summary>
-        [XmlElement(Order = 12)]
+        [XmlElement(Order = 13)]
         public String Stage { get; set; }
         public bool ShouldSerializeStage()
         {
@@ -189,7 +199,7 @@ public bool ShouldSerializeTopicStatus()
         /// <summary>
         /// BimSnippet is an additional file containing information related to one or multiple topics. For example, it can be an IFC file containing provisions for voids.
         /// </summary>
-        [XmlElement(Order = 13)]
+        [XmlElement(Order = 14)]
         public BCFBimSnippet BimSnippet { get; set; }
         public bool ShouldSerializeBimSnippet()
         {
@@ -198,7 +208,7 @@ public bool ShouldSerializeBimSnippet()
         /// <summary>
         /// DocumentReference provides a means to associate additional payloads or links with topics. The references may point to a file within the .bcfzip or to an external location.
         /// </summary>
-        [XmlElement(ElementName = "DocumentReference", Order = 14)]
+        [XmlElement(ElementName = "DocumentReference", Order = 15)]
         public List<BCFDocumentReference> DocumentReferences;
         public bool ShouldSerializeDocumentReferences()
         {
@@ -207,7 +217,7 @@ public bool ShouldSerializeDocumentReferences()
         /// <summary>
         /// Relation between topics (Clash -> PfV -> Opening)
         /// </summary>
-        [XmlElement(ElementName = "RelatedTopic", Order = 15)]
+        [XmlElement(ElementName = "RelatedTopic", Order = 16)]
         public List<BCFRelatedTopic> RelatedTopics;
         public bool ShouldSerializeRelatedTopics()
         {
@@ -241,6 +251,7 @@ public BCFTopic(XElement node)
             Description = (String)node.Element("Description") ?? "";
             Priority = (String)node.Element("Priority") ?? "";
             Index = (int?)node.Element("Index") ?? null;
+            Labels = (String)node.Element("Labels") ?? "";
             CreationDate = (DateTime?)node.Element("CreationDate") ?? null;
             CreationAuthor = (String)node.Element("CreationAuthor") ?? "";
             ModifiedDate = (DateTime?)node.Element("ModifiedDate") ?? null;