▁an ▁optional ▁ ▁part ▁of ▁fis cal ▁policy ▁which ▁diff ers ▁from ▁mand atory ▁sp ending ▁for ▁ent it lement ▁programs ▁in ▁the ▁federal ▁budget . ▁ ▁De fin itions ▁In ▁ 2 0 0 6 ▁the ▁Cong r essional ▁Research ▁Service ▁( CR S ) ▁compiled ▁a ▁report ▁on ▁the ▁use ▁of ▁ear marks ▁in ▁th ir teen ▁App ropri ation ▁Act s ▁from ▁ 1 9 9 4 ▁through ▁ 2 0 0 5 ▁in ▁which ▁they ▁noted ▁that ▁there ▁was ▁" not ▁a ▁single ▁definition ▁of ▁the ▁term ▁ear mark ▁accepted ▁by ▁all ▁pract ition ers ▁and ▁obser vers ▁of ▁the ▁appropri ations ▁process , ▁nor ▁[ was ] ▁there ▁a ▁standard ▁ear mark ▁practice ▁across ▁all ▁appropri ation ▁b ills ." ▁It ▁was ▁noted ▁at ▁that ▁time , ▁that ▁while ▁the ▁C RS ▁did ▁not ▁summar ize ▁ear marks ▁that ▁they ▁came ▁in ▁two ▁vari eties : ▁hard ▁ear marks , ▁or ▁" hard marks ", ▁found ▁in ▁legisl ation , ▁and ▁soft ▁ear marks , ▁or ▁" soft marks ", ▁found ▁in ▁the ▁text ▁of ▁con gression al ▁committee ▁reports . ▁Hard ▁ear marks ▁are ▁leg ally ▁binding , ▁whereas ▁soft ▁ear marks ▁are ▁not ▁but ▁are ▁custom arily ▁acted ▁upon ▁as ▁if ▁they ▁were . ▁The ▁C RS ▁did ▁not ▁aggregate ▁the ▁" v ary ing ▁definitions " ▁as ▁the ▁result ▁would ▁be ▁invalid . ▁ ▁By ▁ 2 0 0 6 , ▁the ▁definition ▁most ▁widely ▁used , ▁developed ▁by ▁the ▁Cong r essional ▁Research ▁Service