protected override void WriteString(ref int pos, string value)
            {
                int stringID;

                if (!string.IsNullOrEmpty(value))
                {
                    stringID = _strings.Add(value) + 1;
                }
                else
                {
                    stringID = 0;
                }

                _blob.Write7BitEncodedInt(ref pos, stringID);
            }