Indicates that the numeric string can be in exponential notation. The NumberStyles.AllowExponent flag allows the parsed string to contain an exponent that begins with the "E" or "e" character and that is followed by an optional positive or negative sign and an integer. In other words, it successfully parses strings in the form nnnExx, nnnE+xx, and nnnE-xx. It does not allow a decimal separator or sign in the significand or mantissa; to allow these elements in the string to be parsed, use the NumberStyles.AllowDecimalPoint and NumberStyles.AllowLeadingSign flags, or use a composite style that includes these individual flags.