Prism Bnf

<number> ::= "+" <unsigned> | "-" <unsigned> | <unsigned>
<unsigned> ::= "NaN" | "Infinity" | <decimal> | <decimal> <exponent>
<decimal> ::= <integer> | "." <non-zero-integer> | <non-zero-integer> "." | <integer> "." <integer>

<exponent> ::= <exponent-char> <exponent-sign> <integer>
<exponent-char> ::= "e" | "E"
<exponent-sign> ::= "+" | "-" | ""

<integer> ::= "0" | <non-zero-integer>
<non-zero-integer> ::= <non-zero-digit> | <non-zero-digit> <digits>

<digits> ::= <digit> | <digit> <digits>
<digit> ::= "0" | <non-zero-digit>
<non-zero-digit> ::= "1" | "2" | "3" | "4" | "5" | "6" | "7" | "8" | "9"

<number> ::= ["+" | "-"] <unsigned>
<unsigned> ::= "NaN" | "Infinity" | <decimal> [<exponent>]
<decimal> ::= <integer> ["." <integer>] | "." <non-zero-integer> | <non-zero-integer> "."
<exponent> ::= ( "e" | "E" ) ["+" | "-"] <integer>

<integer> ::= "0" | <non-zero-integer>
<non-zero-integer> ::= <non-zero-digit> [<digit>...]

<digit> ::= "0" | <non-zero-digit>
<non-zero-digit> ::= "1" | "2" | "3" | "4" | "5" | "6" | "7" | "8" | "9"