Er - partly answering one of my questions is this Ford Acronyms page:
http://www.ford-trucks.com/forums/10...finitions.html
FEPS: Flash EEPROM Programming Signal. 18 volt DC signal sent by the scan tool to initiate PCM reprogramming.
And interestingly enough, the Pinout label on the PCM Module says 'FEPS' on the pin that connects to OBD2 port pin 13. Nice.
Lukeyson