private void WriteXmlStartTagsForPackageProperties()
        {
            _xmlWriter.WriteStartDocument();

            // <coreProperties
            _xmlWriter.WriteStartElement(PackageXmlStringTable.GetXmlString(PackageXmlEnum.CoreProperties),                  // local name
                                         PackageXmlStringTable.GetXmlString(PackageXmlEnum.PackageCorePropertiesNamespace)); // namespace

            // xmlns:dc
            _xmlWriter.WriteAttributeString(PackageXmlStringTable.GetXmlString(PackageXmlEnum.XmlNamespacePrefix),
                                            PackageXmlStringTable.GetXmlString(PackageXmlEnum.DublinCorePropertiesNamespacePrefix),
                                            null,
                                            PackageXmlStringTable.GetXmlString(PackageXmlEnum.DublinCorePropertiesNamespace));

            // xmlns:dcterms
            _xmlWriter.WriteAttributeString(PackageXmlStringTable.GetXmlString(PackageXmlEnum.XmlNamespacePrefix),
                                            PackageXmlStringTable.GetXmlString(PackageXmlEnum.DublincCoreTermsNamespacePrefix),
                                            null,
                                            PackageXmlStringTable.GetXmlString(PackageXmlEnum.DublinCoreTermsNamespace));
            // xmlns:xsi
            _xmlWriter.WriteAttributeString(PackageXmlStringTable.GetXmlString(PackageXmlEnum.XmlNamespacePrefix),
                                            PackageXmlStringTable.GetXmlString(PackageXmlEnum.XmlSchemaInstanceNamespacePrefix),
                                            null,
                                            PackageXmlStringTable.GetXmlString(PackageXmlEnum.XmlSchemaInstanceNamespace));
        }
        // This method validates xsi:type="dcterms:W3CDTF"
        // The value of xsi:type is a qualified name. It should have a prefix that matches
        //  the xml namespace (ns) within the scope and the name that matches name
        // The comparisons should be case-sensitive comparisons
        internal static void ValidateXsiType(XmlReader reader, object ns, string name)
        {
            // Get the value of xsi;type
            string typeValue = reader.GetAttribute(PackageXmlStringTable.GetXmlString(PackageXmlEnum.Type),
                                                   PackageXmlStringTable.GetXmlString(PackageXmlEnum.XmlSchemaInstanceNamespace));

            // Missing xsi:type
            if (typeValue == null)
            {
                throw new XmlException(SR.Format(SR.UnknownDCDateTimeXsiType, reader.Name),
                                       null, ((IXmlLineInfo)reader).LineNumber, ((IXmlLineInfo)reader).LinePosition);
            }

            int index = typeValue.IndexOf(':');

            // The value of xsi:type is not a qualified name
            if (index == -1)
            {
                throw new XmlException(SR.Format(SR.UnknownDCDateTimeXsiType, reader.Name),
                                       null, ((IXmlLineInfo)reader).LineNumber, ((IXmlLineInfo)reader).LinePosition);
            }

            // Check the following conditions
            //  The namespace of the prefix (string before ":") matches "ns"
            //  The name (string after ":") matches "name"
            if (!object.ReferenceEquals(ns, reader.LookupNamespace(typeValue.Substring(0, index))) ||
                string.CompareOrdinal(name, typeValue.Substring(index + 1, typeValue.Length - index - 1)) != 0)
            {
                throw new XmlException(SR.Format(SR.UnknownDCDateTimeXsiType, reader.Name),
                                       null, ((IXmlLineInfo)reader).LineNumber, ((IXmlLineInfo)reader).LinePosition);
            }
        }
        // Write the property elements and clear _dirty.
        private void SerializeDirtyProperties()
        {
            Debug.Assert(_xmlWriter != null);

            // Create a property element for each non-null entry.
            foreach (KeyValuePair <PackageXmlEnum, object> entry in _propertyDictionary)
            {
                Debug.Assert(entry.Value != null);

                PackageXmlEnum propertyNamespace = PackageXmlStringTable.GetXmlNamespace(entry.Key);

                _xmlWriter.WriteStartElement(PackageXmlStringTable.GetXmlString(entry.Key),
                                             PackageXmlStringTable.GetXmlString(propertyNamespace));

                if (entry.Value is Nullable <DateTime> )
                {
                    if (propertyNamespace == PackageXmlEnum.DublinCoreTermsNamespace)
                    {
                        // xsi:type=
                        _xmlWriter.WriteStartAttribute(PackageXmlStringTable.GetXmlString(PackageXmlEnum.Type),
                                                       PackageXmlStringTable.GetXmlString(PackageXmlEnum.XmlSchemaInstanceNamespace));

                        // "dcterms:W3CDTF"
                        _xmlWriter.WriteQualifiedName(W3cdtf,
                                                      PackageXmlStringTable.GetXmlString(PackageXmlEnum.DublinCoreTermsNamespace));

                        _xmlWriter.WriteEndAttribute();
                    }

                    // Use sortable ISO 8601 date/time pattern. Include second fractions down to the 100-nanosecond interval,
                    // which is the definition of a "tick" for the DateTime type.
                    _xmlWriter.WriteString(XmlConvert.ToString(((Nullable <DateTime>)entry.Value).Value.ToUniversalTime(), "yyyy-MM-ddTHH:mm:ss.fffffffZ"));
                }
                else
                {
                    // The following uses the fact that ToString is virtual.
                    _xmlWriter.WriteString(entry.Value.ToString());
                }

                _xmlWriter.WriteEndElement();
            }

            // Mark properties as saved.
            _dirty = false;
        }
        // Deserialize properties part.
        private void ParseCorePropertyPart(PackagePart part)
        {
            XmlReaderSettings xrs = new XmlReaderSettings();

            xrs.NameTable = _nameTable;
            using (Stream stream = part.GetStream(FileMode.Open, FileAccess.Read))

                // Create a reader that uses _nameTable so as to use the set of tag literals
                // in effect as a set of atomic identifiers.
                using (XmlReader reader = XmlReader.Create(stream, xrs))
                {
                    //This method expects the reader to be in ReadState.Initial.
                    //It will make the first read call.
                    PackagingUtilities.PerformInitialReadAndVerifyEncoding(reader);

                    //Note: After the previous method call the reader should be at the first tag in the markup.
                    //MoveToContent - Skips over the following - ProcessingInstruction, DocumentType, Comment, Whitespace, or SignificantWhitespace
                    //If the reader is currently at a content node then this function call is a no-op
                    if (reader.MoveToContent() != XmlNodeType.Element ||
                        (object)reader.NamespaceURI != PackageXmlStringTable.GetXmlStringAsObject(PackageXmlEnum.PackageCorePropertiesNamespace) ||
                        (object)reader.LocalName != PackageXmlStringTable.GetXmlStringAsObject(PackageXmlEnum.CoreProperties))
                    {
                        throw new XmlException(SR.CorePropertiesElementExpected,
                                               null, ((IXmlLineInfo)reader).LineNumber, ((IXmlLineInfo)reader).LinePosition);
                    }

                    // The schema is closed and defines no attributes on the root element.
                    if (PackagingUtilities.GetNonXmlnsAttributeCount(reader) != 0)
                    {
                        throw new XmlException(SR.Format(SR.PropertyWrongNumbOfAttribsDefinedOn, reader.Name),
                                               null, ((IXmlLineInfo)reader).LineNumber, ((IXmlLineInfo)reader).LinePosition);
                    }

                    // Iterate through property elements until EOF. Note the proper closing of all
                    // open tags is checked by the reader itself.
                    // This loop deals only with depth-1 start tags. Handling of element content
                    // is delegated to dedicated functions.
                    int attributesCount;

                    while (reader.Read() && reader.MoveToContent() != XmlNodeType.None)
                    {
                        // Ignore end-tags. We check element errors on opening tags.
                        if (reader.NodeType == XmlNodeType.EndElement)
                        {
                            continue;
                        }

                        // Any content markup that is not an element here is unexpected.
                        if (reader.NodeType != XmlNodeType.Element)
                        {
                            throw new XmlException(SR.PropertyStartTagExpected,
                                                   null, ((IXmlLineInfo)reader).LineNumber, ((IXmlLineInfo)reader).LinePosition);
                        }

                        // Any element below the root should open at level 1 exclusively.
                        if (reader.Depth != 1)
                        {
                            throw new XmlException(SR.NoStructuredContentInsideProperties,
                                                   null, ((IXmlLineInfo)reader).LineNumber, ((IXmlLineInfo)reader).LinePosition);
                        }

                        attributesCount = PackagingUtilities.GetNonXmlnsAttributeCount(reader);

                        // Property elements can occur in any order (xsd:all).
                        object         localName      = reader.LocalName;
                        PackageXmlEnum xmlStringIndex = PackageXmlStringTable.GetEnumOf(localName);
                        string         valueType      = PackageXmlStringTable.GetValueType(xmlStringIndex);

                        if (Array.IndexOf(s_validProperties, xmlStringIndex) == -1) // An unexpected element is an error.
                        {
                            throw new XmlException(
                                      SR.Format(SR.InvalidPropertyNameInCorePropertiesPart, reader.LocalName),
                                      null, ((IXmlLineInfo)reader).LineNumber, ((IXmlLineInfo)reader).LinePosition);
                        }

                        // Any element not in the valid core properties namespace is unexpected.
                        // The following is an object comparison, not a string comparison.
                        if ((object)reader.NamespaceURI != PackageXmlStringTable.GetXmlStringAsObject(PackageXmlStringTable.GetXmlNamespace(xmlStringIndex)))
                        {
                            throw new XmlException(SR.UnknownNamespaceInCorePropertiesPart,
                                                   null, ((IXmlLineInfo)reader).LineNumber, ((IXmlLineInfo)reader).LinePosition);
                        }

                        if (string.CompareOrdinal(valueType, "String") == 0)
                        {
                            // The schema is closed and defines no attributes on this type of element.
                            if (attributesCount != 0)
                            {
                                throw new XmlException(SR.Format(SR.PropertyWrongNumbOfAttribsDefinedOn, reader.Name),
                                                       null, ((IXmlLineInfo)reader).LineNumber, ((IXmlLineInfo)reader).LinePosition);
                            }

                            RecordNewBinding(xmlStringIndex, GetStringData(reader), true /*initializing*/, reader);
                        }
                        else if (string.CompareOrdinal(valueType, "DateTime") == 0)
                        {
                            int allowedAttributeCount = (object)reader.NamespaceURI ==
                                                        PackageXmlStringTable.GetXmlStringAsObject(PackageXmlEnum.DublinCoreTermsNamespace)
                                                        ? 1 : 0;

                            // The schema is closed and defines no attributes on this type of element.
                            if (attributesCount != allowedAttributeCount)
                            {
                                throw new XmlException(SR.Format(SR.PropertyWrongNumbOfAttribsDefinedOn, reader.Name),
                                                       null, ((IXmlLineInfo)reader).LineNumber, ((IXmlLineInfo)reader).LinePosition);
                            }

                            if (allowedAttributeCount != 0)
                            {
                                ValidateXsiType(reader,
                                                PackageXmlStringTable.GetXmlStringAsObject(PackageXmlEnum.DublinCoreTermsNamespace),
                                                W3cdtf);
                            }

                            RecordNewBinding(xmlStringIndex, GetDateData(reader), true /*initializing*/, reader);
                        }
                        else // An unexpected element is an error.
                        {
                            Debug.Fail("Unknown value type for properties");
                        }
                    }
                }
        }