1. Scope 1.1 This Standard applies to the safe storage, handling, and use of high-pressure oxygen cylinders, liquid oxygen systems, and oxygen concentrators used in home, domiciliary, and healthcare settings. 1.2 This Standard includes requirements for maximum aggregate storage quantities of liquid and gaseous oxygen. 1.3 The correct interpretation of Clauses depends on the interpretation of the words shall, should, and may. Shall is mandatory; should is recommendatory; may is permissive. Figures, Tables, and accompanying legends are mandatory; the appendices and notes are not mandatory.