Zoning is a method used to indicate willingness to escalate (primarily, but not only) physical scenes by dividing the game area into different zones where different levels of rules apply. Players choose when to enter the different zones or when to bring a scene into a zone to ecalate or de-escalate what is happening.
In planning the organizers look at what areas are naturally occurring at the game site. They assign different rules to different areas and then communicate this to the players before the game. It is possible to only allow physical violence in one area, or to say that altercations in a specific area might result in character death. To enter an area with harsher rules should be based on all players actively consenting to do so, but players can invite others to come with them to another zone.
It is possible this came from a few Swedish boffer larps that zoned the village as "safe", the forrest as "possibility of fight" and the field as "possible character death". The Swedish fantasy larp Lazarus uses it today with a "family meadow" where nothing to scary will happy, and intermediate meadow and a high intensity meadow.