Which is NOT an ability of timeline Events?

In the HubSpot Data Integration certification, editing data from an external system is identified as NOT an ability of Timeline Events because Timeline Events are strictly "write-only" historical logs intended to display activity within HubSpot. While they are highly powerful for segmenting lists, triggering workflows based on specific behavioral milestones, and visualizing engagement in HubSpot reports, they do not facilitate a bidirectional sync or provide the ability to push data updates back to the source software. Unlike CRM objects, which can store stateful data that is synced back and forth, Timeline Events are immutable snapshots of a single point in time, serving as a reference for what happened rather than acting as a tool for managing or modifying the records in the external system.