Thank you. Is the following safe to assume?

All log files up to the point of the NEW FULL database backup are unusable and could be deleted. Even the though the log chain is still intact, the log backup immediately following the full database backup is the new starting point? (Log files before the new full database backup can't be applied)

Also, there is no command or recording within SQL Server for this. You just have to look at the date/time of the log backup to make sure it falls after the New Full database backup?

is that correct?