Traffic Light Protocol (TLP) us way of classifying data, and it's become very popular because it's so simple. There are 4 levels, generally.
Basically any kind of document or information should be able to be sorted into one of these buckets.
Clear means you can share this with literally anyone and it doesn't matter.
Green means it should probably stay within the district.
Red means there are a few very specific individuals who should see this, and absolutely no one else.
Yellow is pretty much anything inbetween Red and Green. Sensitive stuff, but it's generally OK to loop in people when you need to.