From CustomCoD Wiki
Autosaves/checkpoints are a common functionality in Singleplayer/Co-Op, they provide players spots to pick up from in the event that they die.
There are two common ways to execute an autosave, by trigger or by script.
Make a trigger of your choice and give it the Key Value Pair:
When the trigger is triggered, it will make an autosave.
To make an autosave via script, we pass a save name string into autosave_by_name function.
autosave_by_name( "Player just grabbed documents" );
Source Treyarch Wiki