ISO 8764-1:2004 specifies the shapes and dimensions, technical requirements and torque test methods for the tips of hand drivers and of machine-operated bits for cross-recessed head screws. It specifies two forms of driver tips: form PH for form H recesses and form PZ for form Z recesses. (H and Z form recesses are specified in ISO 4757, while general requirements, lengths of blades and marking of hand-operated screwdrivers are given in ISO 8764-2.)