If line LM (0, 9) is congruent to line MN (0, 1) what is the order pair for point M

How do two letters and an ordered pair represent a line? (as in LM(0,9))

An ordered pair represents a point. Which point on the line does the ordered pair represent?

To be congruent, two lines must have the same length. L must be the same distance from M as N is.