JSON: Only a single leading minus sign is permitted; a leading plus sign or multiple signs are not permitted.
Exponents are permitted but not resolved. 3E4 is returned as 3E4.
Leading zeros are not permitted. Trailing zeros are not removed.
Integer zero fractions must have a zero integer. Therefore, .66 and 000.66 are not valid JSON numbers, but 0.66 and 0.660000 are valid JSON numbers.
A trailing decimal separator is not permitted.
Zero values are not converted: 0.0, -0, and -0.000 are returned unchanged as valid JSON numbers.