  We consider the cos(phi) dependence of the longitudinal double-spin asymmetry
for charged pion electroproduction in semi-inclusive deep inelastic scattering,
emphasizing intrinsic transverse momentum effects. This azimuthal asymmetry
allows to measure the cos(phi) moments of the unpolarized and double-spin
cross-section, simultaneously. The size of the asymmetry, in the approximation
where all twist-3 interaction-dependent distribution and fragmentation
functions are set to zero, is estimated for HERMES kinematics; both the
spin-independent and the double-spin cos(phi) moments are predicted to be
sizeable and negative.
