private int computeIndexFileLengthInWords(ShapeFileIndex index)
		{
			int length = ShapeFileConstants.HeaderSizeBytes / 2;

			length += index.Count * ShapeFileConstants.IndexRecordByteLength / 2;

			return length;
		}
		private int computeMainFileLengthInWords(ShapeFileIndex index)
		{
			int length = ShapeFileConstants.HeaderSizeBytes / 2;

			foreach (KeyValuePair<uint, ShapeFileIndex.IndexEntry> kvp in index)
			{
				length += kvp.Value.Length + ShapeFileConstants.ShapeRecordHeaderByteLength / 2;
			}

			return length;
		}