Full Backup Job
When you include the data and the commit log in a full backup job, then the commit log is linked to the full data backup job and the software ages the commit log job after the corresponding data full job is aged.
When the software ages a full job, it ages all the commit log backup jobs that ran during the cycle.
Incremental Backup Job
When you include the data and the commit log in an incremental backup job, then the commit log is linked to the incremental data backup job and are linked to previous available incremental data jobs the software ages the commit log job after the corresponding data full job is aged.
Standalone Commit Log Jobs
If you have a commit log only backup job, then the software links it to the previous available data backup job.