Downfield is "in or into the part of the field toward which the offensive team is headed," according to the Merriam-Webster dictionary (1), and is consistent with the use of "downfield" in the football penalty, Ineligible Receiver Downfield. Unfortunately, as of this date (10-23-11), Merriam-Webster has the same definition for upfield as it does for downfield (2)!
(1) http://www.merriam-webster.com/dictionary/downfield
(2) http://www.merriam-webster.com/dictionary/upfield
Arthur Upfield's birth name is Arthur William Upfield.
I cannot speak to those specific rules of football, but in general, lineman are allowed to be downfield on any pass where the ball is caught BEHIND the line of scrimmage.
A punt in football tends to be when the football is hit with the toes, rather then the inside of the foot or the laces of the boot. Punt is sometimes used to describe hitting the ball very hard and out of control. 'punt it' upfield, rather then pass it upfield. Punt also is a slang term for putting a bet on. 'having a punt on the horses'
He was not heavy, and didn't have the muscle to throw the ball downfield
A hitch is a pattern where the receiver runs upfield then stops and moves toward QB for the catch
Arthur Upfield died in 1964.
In American football, offensive linemen can be a maximum of 1 yard downfield at the time the ball is thrown on a forward pass. Beyond this yard, they would be considered ineligible receivers and an illegal man downfield penalty would be called.
Upfield railway station was created in 1889.
Upfield railway line was created in 1884.
The bootleg is when the quarterback rolls out to the side and either throws it while running or keeps running upfield.
Downfield F.C. was created in 1912.
A pass route in which the receiver heads downfield, then quickly turns back toward the line of scrimmage.