Lack of action rule......
In a nutshell, this rule forced the team which was behind in the score to "force the action" of the game. If the team with the ball was behind, they had 5 seconds to penetrate the 28 foot line, which is where the hash mark on many courts is. Whenever they would bring the ball back beyond that point, a new 5 count would begin. This rule was not invoked if the defense was playing aggressive defense in the mid-court area (the area between the 28' line and the division line).
If the defense was behind, they had 5 seconds to go "create the action" by playing agressive defense in the mid-court area.
If whichever team was responsible for forcing the action did not before the 5 second count, then a verbal "play ball" command would be given from the covering official. The team then had 5 seconds to create action as described above. The next time that the team did not "force the action" during that period, it was a technical foul.
My old feeble mind now needs a rest, having been forced to remember such ancient history
