Lock-codes were used on both the exterior and interior entrance-ways of buildings. Some doors were programmed with double-lock codes.
Lock-codes were used, for example, on the security doors of Granta Omega's Blackwater Systems facility on the outskirts of Falleen Throne, capital city of Falleen, before the Clone Wars. Some of these doors were double-coded.
Lock-codes were also used for the entrance-ways of civilian homes, such as those on Coruscant, around 7 ABY. To prevent the spread of the Krytos virus, some infected individuals would seal the entrances of their homes and scramble the lock-codes to keep others away. Lock-descrambling units were used by health officials in an attempt to get to these victims.
A lock-pad was the input device for the lock-code, typically found on the entrance-ways themselves.