▁SC SI ▁Per i pher al ▁Device ▁Type ▁( P DT ). ▁Sub class ▁codes ▁specify ▁the ▁following ▁command ▁sets : ▁Red u ced ▁Block ▁Comm ands ▁( R BC ) ▁S FF - 8 0 2 0 i , ▁M MC - 2 ▁( used ▁by ▁A TA PI - style ▁CD ▁and ▁DVD ▁drives ) ▁Q IC - 1 5 7 ▁( ta pe ▁drives ) ▁Un iform ▁Flo ppy ▁Interface ▁( U FI ) ▁S FF - 8 0 7 0 i ▁( used ▁by ▁AR MD - style ▁devices ) ▁SC SI ▁transparent ▁command ▁set ▁( use ▁" in qu iry " ▁to ▁obtain ▁the ▁P DT ) ▁ ▁The ▁specification ▁does ▁not ▁require ▁a ▁particular ▁file ▁system ▁on ▁conform ing ▁devices . ▁Based ▁on ▁the ▁specified ▁command ▁set ▁and ▁any ▁subset , ▁it ▁provides ▁a ▁means ▁to ▁read ▁and ▁write ▁se ctors ▁of ▁data ▁( similar ▁to ▁the ▁low - level ▁interface ▁used ▁to ▁access ▁a ▁hard ▁drive ). ▁Oper ating ▁systems ▁may ▁treat ▁a ▁USB ▁mass - storage ▁device ▁like ▁a ▁hard ▁drive ; ▁users ▁may ▁partition ▁it ▁in ▁any ▁format ▁( such ▁as ▁MB R ▁and ▁G PT ), ▁and ▁format ▁it ▁with ▁any ▁file ▁system . ▁ ▁Because ▁of ▁its ▁relative ▁simplicity , ▁the ▁most - common ▁file ▁system ▁on ▁embedded ▁devices ▁such ▁as ▁USB ▁flash ▁drives , ▁cam eras , ▁or ▁digital ▁audio ▁players ▁is ▁Microsoft ' s ▁F AT ▁or ▁F AT 3 2 ▁file ▁system ▁( with ▁optional ▁support ▁for ▁long ▁fil