É específico para enrolar. De man curl
:
--data-binary <data>
(HTTP) This posts data exactly as specified with no extra processing whatsoever.
If you start the data with the letter @, the rest should be a filename. Data is
posted in a similar manner as --data-ascii does, except that newlines are preserved
and conversions are never done.
If this option is used several times, the ones following the first will append data
as described in -d, --data.