▁a ▁ge oc oding , ▁rather ▁than ▁address ▁identification ▁system : ▁an ▁ 8 ▁character ▁al phan umeric ▁code ▁calculated ▁from ▁latitude ▁and ▁longitude ▁to ▁an ▁accuracy ▁of ▁within ▁ 6 ▁metres ▁in ▁any ▁direction . ▁It ▁includes ▁a ▁check sum ▁character . ▁The ▁equivalent ▁code ▁for ▁the ▁Mid land ▁Regional ▁Hospital ▁is ▁R FT - 4 1 - M 4 6 ▁. ▁ ▁Loc 8 ▁codes ▁cannot ▁be ▁computed ▁directly ▁to ▁or ▁from ▁a ▁ge ographical ▁location ▁without ▁the ▁assistance ▁of ▁software ▁produced ▁by ▁Loc 8 ▁Code . ▁The ▁lic ence ▁conditions ▁for ▁the ▁code ▁prohib it ▁any ▁third ▁party ▁from ▁reverse - engine ering ▁the ▁algorithm . ▁ ▁The ▁Loc 8 ▁code ▁consists ▁of ▁at ▁least ▁three ▁discrete ▁parts , ▁each ▁of ▁which ▁im parts ▁increasing ▁accuracy ▁of ▁the ▁location . ▁T aking ▁the ▁previous ▁example , ▁if ▁the ▁code ▁is ▁trunc ate ▁to ▁its ▁first ▁three ▁characters ▁(" R FT ") ▁an ▁area ▁of ▁approximately ▁ 3 . 5   km ▁square ▁is ▁defined ; ▁the ▁addition ▁of ▁the ▁last ▁three ▁characters ▁(" R FT - M 4 6 ") ▁narrow s ▁this ▁down ▁to ▁an ▁area ▁of ▁ 1 2 0 ▁square ▁metres ▁and ▁provides ▁a ▁check sum ▁digit ▁(" 6 "). ▁ ▁Some ▁basic ▁efforts ▁are ▁made ▁to ▁avoid ▁Loc 8 ▁C odes ▁being ▁accident ally ▁parsed ▁as ▁Royal ▁Mail ▁post codes ▁post ▁codes , ▁particularly ▁those ▁for ▁addresses ▁in ▁Northern ▁Ireland . ▁The ▁coding ▁also ▁avoid s ▁opt ically - similar ▁characters ▁( e . g .,