▁south - west . ▁The ▁numbers ▁are ▁not ▁used ▁in ▁the ▁E ir code ▁system , ▁with ▁routing ▁keys ▁in ▁the ▁C ork ▁area ▁instead ▁beginning ▁with ▁the ▁letter ▁' T '. ▁ ▁E ir code ▁ ▁The ▁launch ▁of ▁a ▁national ▁post code ▁system ▁( E ir code , ▁Irish ▁) ▁in ▁Ireland ▁began ▁on ▁ 2 8 ▁April ▁ 2 0 1 4 . ▁The ▁system ▁incorpor ates ▁the ▁existing ▁number ed ▁Dublin ▁postal ▁districts ▁as ▁part ▁of ▁the ▁routing ▁key . ▁E ir code ▁made ▁Ireland ▁the ▁first ▁country ▁in ▁the ▁world ▁to ▁have ▁a ▁unique ▁post code ▁for ▁each ▁address . ▁ ▁The ▁codes , ▁known ▁as ▁" E irc odes ", ▁consist ▁of ▁seven ▁characters . ▁The ▁first ▁three ▁characters , ▁called ▁the ▁" Rout ing ▁Key ", ▁are ▁designed ▁to ▁benefit ▁the ▁postal ▁and ▁log istics ▁industry ▁and ▁contain ▁on ▁average ▁ 1 5 , 0 0 0 ▁addresses ▁each . ▁The ▁Rout ing ▁Key ▁is ▁used ▁to ▁help ▁sort ▁mail , ▁it ▁is ▁the ▁principal ▁Post ▁Town ▁of ▁the ▁address ▁as ▁defined ▁by ▁An ▁Post . ▁The ▁second ▁part ▁of ▁the ▁E ir code , ▁called ▁the ▁" Uni que ▁Identifier ", ▁consists ▁of ▁four ▁characters ▁drawn ▁from ▁a ▁carefully ▁selected ▁set ▁of ▁random ised ▁letters ▁and ▁numbers ▁that ▁identify ▁each ▁individual ▁address . ▁They ▁are ▁stored ▁in ▁a ▁central ▁database , ▁E ir code ▁Address ▁Database ▁( EC AD ), ▁along ▁with ▁other ▁useful ▁ge ographic ▁information ▁including ▁addresses , ▁variants / ali ases ,