When looking at different modes within one simulation study, are the relative displacement numbers only valid within each individual mode, or is the relative displacement valid across modes?  

In other words, if Mode 1 has a max displacement of 1, and Mode 2 has a max displacement of 2, is it valid to view the max displacement of Mode 2 as as twice that of Mode 1, or are the relative displacements only defined within each individual mode?

(I'm aware that the absolute displacement values are not defined unless using a linear dynamic study, so I'm only asking about the standard frequency study.)