The CopiaFacts log file will contain per-document details of the fax pages successfully transmitted and those on which a failure occurred. No log record is written for documents which are completely skipped on a partial retry, nor for documents for which no transmission attempt was made following a failure during transmission of an earlier document.
The effect of these logging rules is that when a failure of call placement occurs (e.g. no answer) only one log record is written, which will have either the document reference of the first document (or that of the cover sheet, if present). The same will happen when no documents are sent at all on a one-call fax transmission.
Some earlier versions of FaxFacts created log records for all documents in a transmission, all with the same error code as the document on which the error occurred. The new smart logging feature never creates a log record for a completely skipped document, but the $log_options logall keyword will cause a log-record to be created for documents which follow a failure of call placement or a failure in mid-transmission.