1st & Goal, or 10?

[Robert Goodman]

Originally Posted by CT1

FED 2-27-5: The line to gain is the yard line established when a new series (first
down) is awarded. Unless there is a penalty following the ready-for-play signal,
the line to gain is 10 yards in advance of the foremost point of the ball when
placed for the first down of the series. lf the line to gain extends into the end zone,
the goal line is the line to gain.

Easiest way to remember is that "first down" by whatever means achieved -- penalty, new possession, line to gain reached (and not a matter of its being a repeated down) -- is just a short way of saying a new series of downs is awarded, in which case the previous line to gain is immaterial.