The field-driven spin reorientation transition in uniaxial in-plane magnetized films is discussed by means of phase diagrams which are obtained from the stability analysis of the thermodynamical potential. A classification of the field induced reorientation is carried out concerning the anisotropy axes in films grown on vicinal and twofold low-index surfaces. It is shown that hard-axis loops with magnetization flop are directly related to the reorientation in field. In the framework of the general theory the hard-axis loops can be precisely analyzed.