see also
e-mark, cordless markingthe plastic injection mold makers mark the inputs and outputs (e1 or s1...9) to facilitate the implementation of the mold, and also the m16...m12 threads to avoid errors and be more productive.
e1p63c portable marking gun
the e1p63c marking machine is chosen because the working environment is related to mold manufacture which are heavy and bulky pieces. the operator is positioned on each side of the part to apply simple alphanumeric markings.