Lvalue

lvalue:
        identifier
        $
        $number
        lvalue [ expression ]
        * expression
        ` expression `
        ( lvalue )

The dollar sign $ is the actual argument list of a function; $number is the number-th argument where number is a decimal integer constant.

An lvalue followed by an expression in square brackets is an lvalue. The intuitive meaning is that of a subscript. The lvalue must have type string or list. The expression must be of integer type.

The unary * operator means indirection: the expression must be a pointer, the result is an lvalue.

An expression enclosed in a pair of ` (open quotes) is a lvalue where the expression must be of string type. The object, referred to by it, is the object having the name identical to the string. For instance, `"A"` is equivalent to the object A.

A parenthesized lvalue is a lvalue which is identical to the unadorned lvalue.