ModbusScaleExpr

Optional ordered op chain applied to the raw value, evaluated left-to-right with NO operator precedence. Format is "[op] [number]" with op choices (+ - * /).

Examples: "*10", "/1000", "+1.5", "+32768 /10".

"+32768 /10" means (raw + 32768) / 10.

The formal grammar is defined below:

<expr>   := <term> (" " <term>)*
<term>   := <op> <number>
<op>     := "+" | "-" | "*" | "/"
<number> := <digits> ["." <digits>] [<exp>]
<exp>    := ("e" | "E") ["+" | "-"] <digits>
<digits> := <digit>+
<digit>  := ('0' - '9')