A data processing form for use with photo-sensing apparatus that detect the presence of indicia at indicia-receiving locations on the form. The form is composed of a sheet of carrier material and plurality of indicia-receiving locations. The indicia-receiving locations are defined by a mutable colored composition including a mutable colorant and an ultraviolet radiation transorber such that the indicia-receiving locations are adapted to become substantially undetectable by photo-sensing apparatus upon irradiating the colored composition with ultraviolet radiation at a dosage level sufficient to irreversibly mutate the colorant. The colored composition may be irradiated with radiation in the ultraviolet region of the ultraviolet spectrum. Also disclosed is a data processing form that includes a plurality of mutable indicia, at least a portion of which are adapted to become substantially undetectable by photo-sensing apparatus upon irradiation with an effective dosage level of ultraviolet radiation such as, for example, ultraviolet radiation. One embodiment of the present invention encompasses a method for improving the readability of a data processing form used in photo-sensing apparatus. Another embodiment of the present invention encompasses a method of modifying indicia on a data processing form used in photo-sensing apparatus.