Lockdown is a fairly small mod aimed towards mod packs which use a pre made map.
Lockdown’s main function is to create duplicates of a given template when creating a new world. The directory for this template can be defined in the config file (however it defaults to .minecraft/template). This template is in no strange format, you can simply copy/rename any existing world to be it. The use of a template over creating a regular world can be toggled in the config file (it is enabled by default).
Lockdown also allows a few GUI elements to be disabled/removed. The button for changing the game mode of the world, the more world options button and the button for multiplayer are all configurable and are disabled by default.