  We study the recovery of functions in real spline spaces from unsigned
sampled values. We consider two types of recovery. The one is to recover
functions locally from finitely many unsigned samples. And the other is to
recover functions on the whole line from infinitely many unsigned samples. In
both cases, we give characterizations for a sequence of distinct points to be a
phaseless sampling sequence, at which any nonseparable function is determined
up to a sign on an interval or on the whole line by its unsigned sampled
values. Moreover, for the case of local recovery, we also study the almost
phaseless sampling and give a necessary and sufficient condition for a sequence
of points to admit local recovery for almost all functions.
