SF Documentation states the following
If a Bulk API request causes a trigger to fire multiple times for chunks of 200 records, governor limits are reset between these trigger invocations for the same HTTP request.
Assuming an SObject has active apex trigger, an insert DML of 800 records via Bulk API would could cause trigger invocations for chunks of 200 records (so, 4 trigger invocations) and the governor limits are reset between each invocation. Would each of these invocation be considered a separate trigger transaction or a part of single combined transaction? I couldn't find any definitive SF documentation that clarifies about the transaction.