▁which ▁is ▁the ▁statement ▁element , ▁and ▁they ▁are ▁associated ▁with ▁Digital ▁Items . ▁ ▁Digital ▁Items ▁and ▁their ▁parts ▁are ▁identified ▁by ▁enc aps ulating ▁uniform ▁resource ▁ident ifiers , ▁which ▁are ▁a ▁compact ▁string ▁of ▁characters ▁for ▁ident ifying ▁an ▁abstract ▁or ▁physical ▁resource . ▁ ▁The ▁elements ▁of ▁a ▁D ID ▁can ▁have ▁zero , ▁one ▁or ▁more ▁descript ors ; ▁each ▁des criptor ▁may ▁contain ▁a ▁statement ▁which ▁can ▁contain ▁an ▁identifier ▁rel ating ▁to ▁the ▁parent ▁element ▁of ▁the ▁statement . ▁Besides ▁the ▁references ▁to ▁the ▁resources , ▁a ▁D ID ▁can ▁include ▁information ▁about ▁the ▁item ▁or ▁its ▁parts . ▁On ▁the ▁left , ▁there ▁is ▁a ▁visual ▁example ▁about ▁the ▁metadata ▁that ▁a ▁music ▁album ▁could ▁have ▁in ▁M PE G - 2 1 . ▁ ▁It ▁is ▁necessary ▁for ▁D II ▁to ▁allow ▁differenti ating ▁between ▁the ▁different ▁sch emas ▁that ▁users ▁can ▁use ▁to ▁describe ▁their ▁content . ▁M PE G - 2 1 ▁D II ▁uses ▁the ▁XML ▁mechanism ▁to ▁do ▁this . ▁ ▁Digital ▁Item ▁Ada pt ation ▁▁▁ ▁Main ly , ▁the ▁key ▁element ▁is ▁to ▁achieve ▁transparent ▁access ▁to ▁distributed ▁advanced ▁multimedia ▁content , ▁by ▁avoid ing ▁users ▁from ▁doing ▁network ▁and ▁terminal ▁installation , ▁management ▁and ▁implementation . ▁This ▁will ▁enable ▁the ▁provision ▁of ▁network ▁and ▁terminal ▁resources ▁on ▁demand ▁to ▁form ▁user ▁communities ▁where ▁multimedia ▁content ▁can ▁be ▁created ▁and ▁shared , ▁always ▁with ▁the ▁agreed / cont ract ed ▁quality , ▁reli ability ▁and ▁flex ibility .