[latex]
File \;\;\; (z) \;\;\; directory \;\;\; (x,y) \\
(x1,y1,z1) \; (x2,y2,z2) \\
source \; directory \; and \; file \; (x1,y1,z1) \\
destination \; directory \; and \; file \; (x2,y2,z2) \\
A \;\; function \;\; \ f \ (x1,y1,z1) \;\; \longrightarrow \;\; (x2,y2,z2)
[/latex]