Various aspects of nonlocality of a quantum wave are discussed. In particul
ar, the question of the possibility of extracting information about the rel
ative phase in a quantum wave is analyzed. it is argued that there is a pro
found difference in the nonlocal properties of the quantum wave between fer
mion and boson particles. The phase of the boson quantum state can be found
from correlations between results of measurements in separate regions. The
se correlations are identical to the Einstein-Podolsky-Rosen (EPR) correlat
ions between two entangled systems. An ensemble of results of measurements
performed on fermion quantum waves does not exhibit the EPR correlations an
d the relative phase of fermion quantum waves cannot be found from these re
sults. The existence of a physical variable (the relative phase) that canno
t be measured locally is the nonlocality aspect of the quantum wave of a fe
rmion.