  We theoretically study the magnetic field orientation dependence of
longitudinal and transverse flux line lattice form factors in uniaxial
superconductors with anisotropy ratio corresponding to YBa_2_Cu_3_O_{7-delta}.
We discuss influences of the anisotropy ratio of coherence length, and
differences between the s-wave and the d_{x^2-y^2}-wave pairings. The
calculations are performed by two methods, the Eilenberger theory and the
London theory comparatively, and we study the cutoff function of the extended
London theory, which will be helpful in the analysis of the small angle neutron
scattering in the vortex states.
