Risk and Safety Statements
Risk and Safety Statements, also known as R/S statements, R/S numbers, R/S phrases, and R/S sentences, is a system of hazard codes and phrases for labeling dangerous chemicals and compounds. The R/S statement of a compound consists of a risk part (R) and a safety part (S), each followed by a combination of numbers.
Source: Wikipedia — Risk and Safety Statements (CC BY-SA 4.0)