Ok, thanks. I'm going to have a close look at those lines of code.
The baud rate and parity and stop values are being passed on to the hardware specific code at that point in a way I don't quite grasp. There are more variables than can be entered in Serial.begin(baud,parity,stop).
I don't understand the space in HardwareSerial Serial (.. how does the syntax get the values from Serial.begin.
It may be a steep learning curve at this point but easier in the long run. I don't need to re-write a complete flexible printer library for a Custom s'print-S thermal printer, just make sure I have the communication correct before sending control codes for a graphic print mode and 8 bit data to it.
Many thanks anyway and I'll keep on trying to figure it out.