From the flag or the end or the run?
 

A's ball on their 20. A1 is tackled at A's 15, but A10 holds at their 19. I enforced from the end of the run. Is that right?

All but one principle is in play. You enforce from the end of the run in this scenario.

Peace

NCAA
No. The foul was in advance of the end of the run but both spots were behind the NZ so enforce from previous spot.

Nfhs
 

This was an NFHS game, but thank you for the clarification on NCAA. I can't imagine how confused I would get if I had to know both!

JRut--thank you as well!

HLC

No problem, but the NCAA rule is a little easier. ;)

Peace

Canadian Ruling
 

CANADIAN RULING:

Minor fouls with the ball behind the line to gain are enforced from PLS (previous spot), DR (down repeated).

Result: Team A same down, but with 10 more yards to go, from their own 10.

If before the 3-minute warning, clock on the ready. If after the 3-minute warning, clock on the snap.