| Name | Description | |
|---|---|---|
 | CallbackData | Internal Callback data. |
| Contents | User-defined parameters. |
| ErrorText | Used for error description. |
| Evaluate | Indicates whether the function is to be evaluated or checked only for syntax. |
| HasError | Indicates that an error was encountered at the time of evaluation. |
| NewValue | Return value of the External$ function. |