-format used for logging file transfers when transfer logging is
-enabled. The format is a text string containing embedded single
-character escape sequences prefixed with a percent (%) character.
+format used for logging file transfers when transfer logging is enabled.
+The format is a text string containing embedded single-character escape
+sequences prefixed with a percent (%) character. An optional numeric
+field width may also be specified between the percent and the escape
+letter (e.g. "%-50n %8l %07p").
+
+The default log format is "%o %h [%a] %m (%u) %f %l", and a "%t [%p] "
+is always prefixed when using the "log file" option.
+(A perl script that will summarize this default log format is included
+in the rsync source code distribution in the "support" subdirectory:
+rsyncstats.)