I got this question wrong on the practical and nee to know what the answer is. What are the markings on the Oxygen Cylinder in the blue painted part on top. ie. (2 [then a symbol] 02+* ), i have looked everywhaere to try to find out what this means, i can't seem to find the answer even in the book. i think it has something to do with the expiration date but i'm not sure. thanks for any help.