<program> ::= <block> "."

<block> ::= ["const" <identifier> "=" <number>  (";" | ({"," <identifier> "=" <number>} ";") )]
        ["var" <identifier> (";" | ({"," <identifier>} ";") )]
        [{  ["proced" <identifier> ";" <block> ";"] ["function" <identifier> "of" "type" <type> ";" <block> ";"]  }]
        <statement>

<statement list> ::= <statement> {";" <statement>}

<statement> ::= [ (<identifier> "=" <expression>) |
          ("call" <identifier>) |
          ("begin" <statement list> "end") |
          ("if" <condition> "then" <statement>) |
          ("for" <identifier> ":=" <expression> "to" <expression> "do" "begin" <statement list> "end") |
          ("while" <conditional> "do" <statement>) ]

<expression> ::= ["+" | "-"] <term> {("+" | "-") <term>}

<term> ::= <factor> {("*" | "/") <factor>}

<factor> ::= <identifier> | <number> | ("(" <expression> ")")

<type> ::= "integer" | "real" | "char"

<conditional> ::= (("odd") | (<expression> ("$"|"%"|"="|"<"|">"|"#"))) <expression>

<uppercase letter> ::= (A|B|C|D|E|F|G|H|I|J|K|L|M|N|O|P|Q|R|S|T|U|V|W|X|Y|Z)

<lowercase letter> ::= (a|b|c|d|e|f|g|h|i|j|k|l|m|n|o|p|q|r|s|t|u|v|w|x|y|z)

<identifier> ::= <lowercase letter> | <uppercase letter>  {<lowercase letter> | <uppercase letter> | <number>}

<number> ::= (0|1|2|3|4|5|6|7|8|9)