public X12StreamReader(Stream stream, Encoding encoding)
{
_reader = new StreamReader(stream, encoding);
char[] header = new char[106];
if (_reader.Read(header, 0, 106) < 106)
throw new ArgumentException("ISA segment and terminator is expected to be at least 106 characters.");
_delimiters = new X12DelimiterSet(header);
_isaSegment = new string(header);
}