Kronotek's Engagement Protocols indicate the level of caution to be used by its agents.
The average Engagement Protocol states that certain people are necessary or even vital to the timestream and should not be killed. Their deaths will affect or even change the timestream. People who are supposed to survive are indicated with a blue aura and important people are indicated by a golden aura.
Open Engagement Protocol states that any people encountered are alrerady doomed. They can be killed without disrupting the timestream.