cos mic ▁set ▁of ▁fixed ▁inter v all ic ▁content , ▁stat able ▁either ▁as ▁a ▁ch ord ▁or ▁as ▁a ▁mel od ic ▁figure ▁or ▁as ▁a ▁combination ▁of ▁both . ▁Its ▁components ▁may ▁be ▁fixed ▁with ▁regard ▁to ▁order , ▁in ▁which ▁event ▁it ▁may ▁be ▁employed , ▁like ▁the ▁twelve - t one ▁set , ▁in ▁its ▁literal ▁transformations . ▁… ▁Ind ividual ▁t ones ▁may ▁function ▁as ▁p iv otal ▁elements , ▁to ▁permit ▁over la pping ▁statements ▁of ▁a ▁basic ▁cell ▁or ▁the ▁linking ▁of ▁two ▁or ▁more ▁basic ▁cells " ▁. ▁ ▁Regarding ▁the ▁post - ton al ▁music ▁of ▁Per le , ▁one ▁the or ist ▁wrote : ▁" Wh ile   ... ▁mont ages ▁of ▁discrete - se em ing ▁elements ▁tend ▁to ▁accum ulate ▁global ▁rh yth ms ▁other ▁than ▁those ▁of ▁t onal ▁progress ions ▁and ▁their ▁rh yth ms , ▁there ▁is ▁a ▁similarity ▁between ▁the ▁two ▁sorts ▁of ▁accum ul ates ▁spatial ▁and ▁temporal ▁relationships : ▁a ▁similarity ▁consisting ▁of ▁generalized ▁arch ing ▁tone - cent ers ▁linked ▁together ▁by ▁shared ▁background ▁refer ential ▁materials " ▁. ▁ ▁Another ▁approach ▁of ▁composition ▁techniques ▁for ▁at onal ▁music ▁is ▁given ▁by ▁Allen ▁For te ▁who ▁developed ▁the ▁theory ▁behind ▁at onal ▁music ▁ ▁For te ▁describes ▁two ▁main ▁operations : ▁trans position ▁and ▁in version . ▁Trans position ▁can ▁be ▁seen ▁as ▁a ▁rotation ▁of ▁t ▁either ▁clock wise ▁or ▁anti - clock wise ▁on ▁a ▁circle , ▁where ▁each ▁note ▁of