What is the requirement for labeling medical gas shut-off valves?

Any examples are for illustrative purposes only.
The labeling shall include:

• the name or chemical symbol for the specific medical gas or vacuum system
• room or areas served
• caution to not close or open the valve except in an emergency

Each room served by the piped medical gas and vacuum zone valves is to be identified. Grouping of consecutive rooms served, like "Procedure Rooms 1-6" should be used with caution to ensure that no unserved location is included with the identification. General statements about the area are not acceptable. 

Hidden shut-off valves, such as those above the ceiling, are to be labeled on or near the valve; its hidden location may be identified by a label, icon, etc., or on a utility system map in accordance with EC.02.05.01 EP 17.

Reference EC.02.05.09 EP11