a communications question requiring a creative solution

Hello there I have been given a question which involves some thinking and understanding of the RS-232 standard but with an imaginary interface. I can use any equipment i want except a cable that connects my pc to a modem.
The standard is called ABC, and it has the following pins:
SG,RTS,DSR,DTR,RX,TX

i have to find which of each of the six pins making up the ABC interface actually correlates to the aforementioned pin functions. It is also mentioned that the terminal will not raise RTS before it receives DSR. Does anyone have any idea how i can find out which pin does, regardless of costs and equipment (except the DTE-DCE cable).

Thanks alot, i know it's an odd question but it would definetly help me see a creative answer to questions i wouldn't know how to tackle