▁out lying ▁islands ▁such ▁as ▁R ath lin ▁Island . ▁The ▁south ▁east ▁corner ▁of ▁the ▁grid ▁is ▁just ▁south ▁of ▁Sk omer , ▁west ▁Wales , ▁at ▁ 5 1 . 3 ° N ▁ 5 . 3 5 ° W . ▁ ▁Red es igned ▁in ▁ 2 0 1 5 , ▁version ▁ 4 , ▁as ▁a ▁spir al ▁of ▁its ▁ 2 5 ▁characters ▁starting ▁with ▁ 2 ▁in ▁the ▁bottom ▁left ▁and ▁continu ing ▁clock wise ▁to ▁X ▁in ▁the ▁middle , ▁the ▁grid ▁has ▁the ▁following ▁format : ▁ ▁Each ▁grid ▁square ▁is ▁subsequently ▁divided ▁into ▁a ▁grid ▁of ▁the ▁same ▁format , ▁and ▁like wise ▁for ▁the ▁resulting ▁squares , ▁until ▁the ▁required ▁precision ▁has ▁been ▁att ained . ▁For ▁each ▁sub div ision , ▁the ▁resulting ▁number ▁or ▁letter ▁is ▁added ▁onto ▁the ▁ge o code . ▁X ▁will ▁always ▁be ▁the ▁centre . ▁The ▁letter ▁V ▁has ▁been ▁removed ▁and ▁replaced ▁with ▁B , ▁which ▁is ▁now ▁upp erm ost ▁top - right ▁so ▁as ▁to ▁place ▁any ▁B ▁codes ▁firm ly ▁within ▁the ▁UK ▁post code ▁area ▁B T ▁and ▁avoid ▁any ▁confusion . ▁ ▁The ▁algorithm ▁works ▁with ▁any ▁combination ▁of ▁ 2 5 ▁characters , ▁or ▁more , ▁as ▁required . ▁This ▁specific ▁grid ▁is ▁optim ised ▁for ▁Ireland . ▁ ▁According ▁to ▁Open Post code . org ▁Ireland , ▁the ▁expected ▁precision ▁is ▁as ▁follows : ▁ ▁A ▁check sum ▁can ▁be ▁generated ▁for ▁codes ▁of ▁any ▁length . ▁A