ORIGINAL: pmw
Hey Rock,
On my computer flight plans SOD = Start Of Descent,
Yup
Back when computers were new to industry and the airlines were one of the first industries to see their value, I worked on a flight plan system being developed. I understand the mainline code is still chugging away. Needless to say the equipment data files would be for newer ac nowadays.....

727s and 1011s aren't exactly used a lot by the major carriers are they.