String annotation defining the supported tracker types for ad event tracking.

This annotation constrains string values to a predefined set of tracker types used throughout the ad serving and tracking system. Tracker types define the specific events or milestones that need to be tracked for analytics, billing, and performance measurement purposes.

The tracker types are organized into categories:

• Response Trackers: For all ad formats (win, click, impression, etc.)

• Native Format Specific: For native ad tracking

• Video Trackers: For video playback events and milestones