public DcmItem(DicomTag tag, DicomVR vr, long pos, Endian endian)
 {
     _tag = tag;
     _vr = vr;
     _streamPosition = pos;
     _endian = endian;
 }

 public void ConstructorPrivateCreator()
 {
     var t = new DicomTag(0x2000, 0x2001, "TEST CREATOR");
     Assert.AreEqual(0x2000, t.Group);
     Assert.AreEqual(0x2001, t.Element);
     Assert.AreEqual("TEST CREATOR", t.PrivateCreator);
 }

 public void ConstructorSimple()
 {
     var t = new DicomTag(0x0028, 0x1203);
     Assert.AreEqual(t.Group, 0x0028);
     Assert.AreEqual(t.Element, 0x1203);
     Assert.IsEmpty(t.PrivateCreator);
 }

 public void Equals()
 {
     var a = new DicomTag(0x0028, 0x9145);
     var b = new DicomTag(0x0028, 0x9146);
     var c = new DicomTag(0x0028, 0x9146);
     var z = default(DicomTag);
     Assert.IsFalse(a.Equals(b));
     Assert.IsFalse(b.Equals(a));
     Assert.IsTrue(b.Equals(c));
     Assert.IsTrue(c.Equals(b));
     Assert.IsFalse(a.Equals(z));
     Assert.IsFalse(b.Equals(z));
 }

 public void EqualsObject()
 {
     var a = new DicomTag(0x0028, 0x9145);
     var b = new DicomTag(0x0028, 0x9146);
     var c = new DicomTag(0x0028, 0x9146);
     var z = default(DicomTag);
     Assert.IsFalse(a.Equals((object)b));
     Assert.IsFalse(b.Equals((object)a));
     Assert.IsTrue(b.Equals((object)c));
     Assert.IsTrue(c.Equals((object)b));
     Assert.IsFalse(a.Equals((object)z));
     Assert.IsFalse(b.Equals((object)z));
 }

 public void OpNEq()
 {
     var a = new DicomTag(0x0028, 0x9145);
     var b = new DicomTag(0x0028, 0x9146);
     var c = new DicomTag(0x0028, 0x9146);
     var z = default(DicomTag);
     Assert.IsTrue(a != b);
     Assert.IsTrue(b != a);
     Assert.IsFalse(b != c);
     Assert.IsFalse(c != b);
     Assert.IsTrue(z != a);
     Assert.IsTrue(a != z);
     Assert.IsTrue(z != b);
     Assert.IsTrue(b != z);
 }

 public void OpEq()
 {
     var a = new DicomTag(0x0028, 0x9145);
     var b = new DicomTag(0x0028, 0x9146);
     var c = new DicomTag(0x0028, 0x9146);
     var z = default(DicomTag);
     Assert.IsFalse(a == b);
     Assert.IsFalse(b == a);
     Assert.IsTrue(b == c);
     Assert.IsTrue(c == b);
     Assert.IsFalse(z == a);
     Assert.IsFalse(a == z);
     Assert.IsFalse(z == b);
     Assert.IsFalse(b == z);
 }

 public DcmUnsignedLong GetUL(DicomTag tag)
 {
     DcmElement elem = GetElement(tag);
     if (elem is DcmUnsignedLong)
         return elem as DcmUnsignedLong;
     if (elem != null)
         throw new DicomDataException("Tried to access element with incorrect VR");
     return null;
 }

 public ushort GetUInt16(DicomTag tag, ushort deflt)
 {
     DcmUnsignedShort us = GetUS(tag);
     if (us != null && us.Length > 0)
         return us.GetValue();
     return deflt;
 }

 public DicomUID GetUID(DicomTag tag)
 {
     DcmUniqueIdentifier ui = GetUI(tag);
     if (ui != null && ui.Length > 0)
         return ui.GetUID();
     return null;
 }

 public DcmUniqueIdentifier GetUI(DicomTag tag)
 {
     DcmElement elem = GetElement(tag);
     if (elem is DcmUniqueIdentifier)
         return elem as DcmUniqueIdentifier;
     if (elem != null)
         throw new DicomDataException("Tried to access element with incorrect VR");
     return null;
 }

 public short GetInt16(DicomTag tag, short deflt)
 {
     DcmSignedShort ss = GetSS(tag);
     if (ss != null && ss.Length > 0)
         return ss.GetValue();
     return deflt;
 }

 protected virtual void OnReceiveNGetRequest(byte presentationID, ushort messageID, DicomUID requestedClass, DicomUID requestedInstance, DicomTag[] attributes)
 {
     SendAbort(DcmAbortSource.ServiceProvider, DcmAbortReason.NotSpecified);
 }

 public DicomVR GetVR(DicomTag tag)
 {
     DcmElement elem = GetElement(tag);
     if (elem == null)
         return null;
     return elem.VR;
 }

 public string GetString(DicomTag tag, string deflt)
 {
     return GetString(tag, 0, deflt);
 }

 public DcmSignedShort GetSS(DicomTag tag)
 {
     DcmElement elem = GetElement(tag);
     if (elem is DcmSignedShort)
         return elem as DcmSignedShort;
     if (elem != null)
         throw new DicomDataException("Tried to access element with incorrect VR");
     return null;
 }

 public DcmItemSequence GetSQ(DicomTag tag)
 {
     DcmItem item = GetItem(tag);
     if (item is DcmItemSequence)
         return item as DcmItemSequence;
     if (item != null)
         throw new DicomDataException("Tried to access element with incorrect VR");
     return null;
 }

 public DcmOtherWord GetOW(DicomTag tag)
 {
     DcmElement elem = GetElement(tag);
     if (elem is DcmOtherWord)
         return elem as DcmOtherWord;
     if (elem != null)
         throw new DicomDataException("Tried to access element with incorrect VR");
     return null;
 }

 public DcmItem GetItem(DicomTag tag)
 {
     DcmItem item = null;
     if (!_items.TryGetValue(tag, out item))
         return null;
     return item;
 }

 public int GetInt32(DicomTag tag, int deflt)
 {
     DcmElement elem = GetElement(tag);
     if (elem != null && elem.Length > 0) {
         if (elem.VR == DicomVR.IS)
             return (elem as DcmIntegerString).GetInt32();
         else if (elem.VR == DicomVR.SL)
             return (elem as DcmSignedLong).GetValue();
         else
             throw new DicomDataException("Tried to access element " + tag.ToString() + " with incorrect VR");
     }
     return deflt;
 }