One of the references is amusing: <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3445694/" rel="nofollow">https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3445694/</a><p>>When asked why his tattoo conflicted with his wishes to be resuscitated, he explained that he had lost a bet playing poker with fellow ancillary hospital staffers while inebriated in his younger years; the loser had to tattoo “D.N.R.” across his chest. [...] It was suggested that he consider tattoo removal to circumvent future confusion about his code status. He stated he did not think anyone would take his tattoo seriously and declined tattoo removal.