wow that's disappointing.
so, now it's time to point out and read section # 5.1.1.4 (2012, 2015 & 2018 editions). FYI also found in older editions.
the fact is, nfpa 99 requirement for B819 type medical gas tubing with the special markings (oxy, med, oxy/med, oxy/acr, acr/med in blue for L and green for K) -
was only first listed in the 1999 edition.
remember the requirement to braze the medical vacuum tubing was first listed in nfpa 99 the 2002 edition.
wow 2018 edition nfpa 99 now has the "CMT" / from the pictures, I have seen it looks like its painted, again double check me on this.
good luck sir.