This part of ISO 3098 specifies the general requirements for lettering, in accordance with the other parts of ISO 3098, to be used in technical product documentation (in particular on technical drawings). It includes basic conventions as well as rules for the application of lettering using the following techniques:a) free-hand lettering (by means of an underlaid “grid”);b) templates and manual lettering instruments;c) dry transfer systems;d) numerically controlled lettering and draughting systems.