Originally Posted by chef2sail
Technically a spring line is led from the bow to a piling behind it or the stern to a piling in front of it.
I was taught that a spring line could leave any cleat and go any direction that prevent for/aft movement. To properly identify it, you would say:
[name of cleat on boat][direction of travel from cleat] spring line.
ie: bow aft spring line, or mid-ship forward spring line, or aft forward spring line, etc.