Backus Naur Form (BNF)
aka Context Free Grammar

Notation:

• Grammar: Collection of Rules
• Rule/Production: LHS -> RHS
• LHS: Non-terminal
• RHS: Terminals + Non-terminals
• Non-terminal: <Abstraction>
• Terminal: Lexeme
• Rule Alternatives: |
• List Description: Recursion

   <declaration>   -> <data-type> <variable-list> ;
   <data-type>      -> int |  float |  char
   <variable-list> ->  <one-variable>
                        | <one-variable> , <variable-list>
   <one-variable>  ->  <variable>
                        | <variable> = <value>
   <variable>      -> count | index | num | sum | var
   <value>         -> 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9                        

Deriving Sentence from Grammar:

• <Start> Non-terminal -> Sentential forms -> Sentence
  Example: <declaration> ->
  int count, index = 1, num;
• Order
  • Leftmost
  • Rightmost