The current implementation of the Code128 symbology class used with RadBarcode throws an InvalidSymbolException for characters with codes greater than 127.

As you can see from this table, there are many special characters in Code128 that have larger codes:

https://en.wikipedia.org/wiki/Code_128#Bar_code_widths

It would be useful to have these in applications which need to modify a reader device's behavior with barcode control characters in order to communicate properly.