This part of ISO 3098 specifies the general requirements for lettering, in accordance with all other parts of this International Standard, 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 (see ISO 9178) and manual lettering instruments; c) dry transfer systems; d) numerically controlled lettering and draughting systems.