Thats pretty much the way I define it.
Staying close to the line and not whipping or weaving back and forth or overrunning very far. Not running the line faster than the dog can handle or than the conditions allow.
Some dogs will gear up or down depending on scenting conditions. Others run, or try to run the same speed every time out and it sometimes causes unnecessary breakdowns in the race.
Here is the defintion according to the ARHA:
3. Line control
a. Line control is simply accuracy in trailing. Speed is not an issue.
b. The hound should pursue the rabbit as fast as the game and scenting conditions allow and still maintain line control and accuracy.