Sign - Script and chart function
                Sign() returns 1, 0 or -1 depending on whether x is a positive number, 0, or a negative number.
Syntax:
Sign(x)
Return data type: numeric
Limitations:
If no numeric value is found, NULL is returned.
Examples and results:
| Examples | Results | 
|---|---|
| 
                                 Sign( 66 )  | 
                            Returns 1 | 
| 
                                 Sign( 0 )  | 
                            Returns 0 | 
| 
                                 Sign( - 234 )  | 
                            Returns -1 |