The help page about furniture modification states "In the furniture pane, you may change its name, the abscissa (X) and the ordinate (Y) of its center".
Center is used because it won't change according to the rotation angle.

...excpet this appears NOT to be correct.
in my example (that i cannot upload! how much time and effort would it save?),

the Furniture item LHS is at 0 on X axis, and its Depth is 703mm.
the "centre" would therefore be 351.5mm; but the Location field actually says "458mm"

so how's that work?