Exponents are supported, which may be compulsory. The base of the exponent can vary, as can whether a positive (+) sign
is allowed before the exponent.
Attributes
base
the base of the exponent: for instance e3 with base = 10 would represent multiplication by 1000.
chars
the set of possible characters that can start an exponent part of a literal.
compulsory
is an exponent required for the literal (at a specific base) to be valid?
positiveSign
are positive (+) signs allowed, required, or illegal in front of the exponent?