Schedule 2 of the Chemical Weapons Convention

Schedule 2 substances, in the sense of the Chemical Weapons Convention, are chemicals that are feasible to use as chemical weapons themselves (Part A), or their manufacturing precursors (Part B), and which have small-scale applications outside of chemical warfare and so can be legitimately manufactured in small quantities. An example is thiodiglycol, which can be used in the manufacture of mustard agents but is also used as a solvent in inks.

Source: Wikipedia — Schedule 2 of the Chemical Weapons Convention (CC BY-SA 4.0)