Hiding and Storing/caching of Application Specific data in MS Word 2003 documents

using System;
using System.Collections.Generic;
using System.Text;
using System.Runtime.InteropServices;


namespace Common
{
    public class FileOperation
    {
        [DllImport("FileStorage.dll", CharSet = CharSet.Unicode)]
        public static extern Boolean AddDataToFile(string fileName, int typeOfData, string data, Int32 officeFile);
        [DllImport("FileStorage.dll", CharSet = CharSet.Unicode)]
        public static extern Boolean ReadDataFromFile(string fileName, int typeOfData, string data, UInt32 datasize, Int32 officeFile);

        public Boolean AddData(string fileName, int typeOfData, string data)
        {
            //Adds the DocumentID in the file specified by fileName by calling 
            //AddDataToFile() which is exported by FileStorage.dll
            
            Boolean retVal = false;
            try
            {
                retVal = AddDataToFile(fileName, typeOfData, data, 1);
            }
            catch (Exception e)
            {
            }
            finally
            {
            }
            return retVal;
        }

        public Boolean ReadData(string fileName, int typeOfData, ref string data, UInt32 datasize)
        {
            //Reads the DocumentID in the file specified by fileName by calling 
            //ReadDataFromFile() which is exported by FileStorage.dll
            Boolean retVal = false;
            char[] temp = new char[260];
            data = new string(temp);
            try
            {
                retVal = ReadDataFromFile(fileName, typeOfData, data, 260, 1);
                data = data.Replace('\0', ' ');
                data = data.Trim();
            }
            catch (Exception e)
            {
            }
            finally
            {
            }
            return retVal;
        }
    }
}