Definition of End Lines
In mining law, the end lines of a claim, as platted or laid down on the ground, sire those which mark its boundaries on the shorter dimension, where it crosses the vein, while the “side lines” are those which mark its longer dimension, where it follows the course of the vein. But with reference to extra-lateral rights, if the claim as a whole crosses the vein, instead of following its course, the end lines will become side lines and vice versa.
That's the definition of End Lines in Black's Law Dictionary 6th Edition. Courtesy of Cekhukum.com.