BNF for "Tiny" language formalization:

1. <program> ---> program <dec part> <statmt
part> end.

2. <dec part> ---> dec <list var> : <type> {? dec
<list var> : <type>}

3. <list var> ---> <ident> {, <ident>}

5. <type> ---> real | int

6. <statmt part> ---> <statement> {! <statement>}

7. <statement> ---> <input> | < output> | <assign>

8. <input> ---> Read ( <list var> )

9. <output> ---> Write < list var>

10. <assig> ---> <ident> = <expression>

11. <expression> ---> <term> {(+|-) <term>}

12. <term> ---> <factor> {(*|/) <factor>} 

13. <factor> ---> <namedigit> | ( <expression> )

14. <namedigit> ---> <ident> | <num>

15. <ident> ---> <letter> {<letter>| <digit>}

16. <num> ---> <digit> {digit>}