7.1.1: There are some ambiguities in the lexical rules for numbers.
(a) In a hexadecimal number, it is not always clear whether an "e" indicates the digit "fourteen" or the beginning of an exponent. Thus, is "#x1e0" to mean "one times sixteen to the zeroth power" or "1 times 256, plus 14 times 16, plus zero"? To remove the ambiguity, Pixie Scheme requires that if a hexadecimal number has an exponent, the exponent must