ment ▁Bü hl mann ▁- ▁based ▁U W ATE C ▁Z H - L 8 ▁AD T ▁MB ▁PM G ▁decom pression ▁model ▁in ▁the ▁Sc ub ap ro ▁Gal ile o ▁d ive ▁computer ▁processes ▁the ▁d ive ▁profile ▁and ▁suggests ▁an ▁intermediate ▁ 2 - min ute ▁stop ▁that ▁is ▁a ▁function ▁of ▁the ▁t issue ▁nit ro gen ▁loading ▁at ▁that ▁time , ▁taking ▁into ▁account ▁the ▁accum ulated ▁nit ro gen ▁from ▁previous ▁div es . ▁Within ▁the ▁H ald an ian ▁logic ▁of ▁the ▁model , ▁at ▁least ▁three ▁compart ments ▁are ▁off g ass ing ▁at ▁the ▁pres cribed ▁depth ▁- ▁the ▁ 5 ▁and ▁ 1 0 ▁minute ▁half ▁time ▁compart ments ▁under ▁a ▁relatively ▁high ▁pressure ▁gradient . ▁Therefore , ▁for ▁decom pression ▁div es , ▁the ▁existing ▁oblig ation ▁is ▁not ▁increased ▁during ▁the ▁stop . ▁ ▁A ▁P DIS ▁is ▁not ▁a ▁mand atory ▁stop , ▁nor ▁is ▁it ▁considered ▁a ▁substitute ▁for ▁the ▁more ▁important ▁shall ow ▁safety ▁stop ▁on ▁a ▁no - stop ▁d ive . ▁Switch ing ▁breath ing ▁gas ▁mix ▁during ▁the ▁as cent ▁will ▁influence ▁the ▁depth ▁of ▁the ▁stop . ▁ ▁The ▁P DIS ▁concept ▁was ▁introduced ▁by ▁Ser gio ▁Angel ini . ▁ ▁De com pression ▁schedule ▁ ▁A ▁decom pression ▁schedule ▁is ▁a ▁specified ▁as cent ▁rate ▁and ▁series ▁of ▁increasing ly ▁shall ower ▁decom pression ▁stops — o ften ▁for ▁increasing ▁amounts ▁of ▁time — that ▁a ▁diver ▁performs ▁to ▁out gas ▁in ert