Lexical Elements

Letter ::=
   "a" | .. | "z" | "A" | .. | "Z" |  "_".

Digit ::=
   "0" | .. | "9".

Symbol ::=
   "!" | "#" | "%" | "&" | "*" | "+" | "-" | "/" | ":" | "<" | 
   "=" | ">" | "?" | "@" | "\" | "^" | "`" | "|" | "~" | "$".

Character ::= legal characters

TypeIde ::= Ide

Ide ::=
   Letter {Letter | Digit}.

Integer ::=
   {Digit}1.

Real ::=
    {Digit}1 "." [{Digit}] [("e" | "E") ("+" | "-") {Digit}1].

Number ::=
    Integer | Real

String ::=
   """ {Character} """.