When SLA timeline is activated, script includes are installed.

SLA timeline adds the following script includes.
Script includeDescription
SLATimeline This script include generates the timeline data for a task SLA record by replaying the task’s history and using the SLATimelineAPI to determine the appropriate stage transitions and timings for the task SLA.
SLATimelineAPI This script include provides a number of functions that simulate how the SLA engine processes a particular task and SLA definition without actually creating any task SLA records.
SLATimeLineV2SNC This script include is used by SLA Timeline internal REST API to inspect audit history of a Task and extract task SLA details to be presented on the UI.
ReadOnlyTaskSLAContoller This script include is a helper script include and is for internal use. This script include is called by SLATimeLineV2SNC to process the task SLA stage details.