<identifier> :== <primul_caractere> <repetat_lc> | <primul_caracter>
<primul_caracter> :== <underscore> | <letter>
<litera_cifra> :== <letter> | <digit>
<repetat_lc> :== <litera_cifra> | <litera_cifra> <repetat_lc>
<letter> :== "A" | "B" | ... | "Z" | "a" | "b" | ... | "z"
<digit> :== "0" | "1" | ... | "9"
<digit_plus> :== "1" | "2" | ... | "9"
<underscore> :== "_"
<const> = <int> | <char> | <string> | <true> | <false>
<int> :== <digit> | <positive_number> | "-" <positive_number>
<cint> :== <digit> | <digit> <cint>
<positive_number> :== <digit_plus> | <digit_plus> <cint>
<string> :== <letter> | <letter> <string>
<OP_P1> = "+" | "-"
<OP_P2> = "*" | "\"
<RELATION> = "==" | ">" | ">=" | "<" | "<=" | "!="
<digit> = "0" | "1" | ... | "9"
<digit_plus> = "1" | "2" | ... | "9"