When a token is read, it is interpreted as a number or symbol. The token is interpreted as a number if it satisfies the syntax for numbers specified in Figure 2--9.
numeric-token ::= !integer | !ratio | !float integer ::= [sign] {decimal-digit}^+ decimal-point | [sign] {digit}^+ ratio ::= [sign] {digit}^+ slash {digit}^+ float ::= [sign] {decimal-digit}{* decimal-point {decimal-digit}^+ [!exponent] } | [sign] {decimal-digit}^+ [decimal-point {decimal-digit}{*] !exponent } exponent ::= exponent-marker [sign] {digit}^+ sign---a sign. slash---a slash decimal-point---a dot. exponent-marker---an exponent marker. decimal-digit---a digit in radix 10. digit---a digit in the current input radix.
Figure 2--9: Syntax for Numeric Tokens
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