C
The way it was explained to me was if the plus sign is on there (+), then it is oxygen cleaned and therefore ok for ice diving. If there is a (-) sign then it is Oxygen cleaned but not ok for cold water use, but can be used for quarry diving - if tank does not have any (+) or (-), if cant be used for either purpose, unless of course it has the DOT ok but only if it is within vaild hydro and VIP

in all cases it can not be filled to its actual capacity because it would require attention to detail and a desire to a good job

As for jail - i suspect only those who make issues of the actual regualtions will be punished, even if they dont make any sense -

i hope that helps
bm