if (tagNo == 0x1f)
        {
            int b = s.read();
            if (b < 31)
            {
                if (b < 0)
                {
                    throw new EOFException("EOF found inside tag value.");
                }
                throw new IOException("corrupted stream - high tag number < 31 found");
            }

            tagNo = b & 0x7f;

            // X.690-0207 8.1.2.4.2