Discrete meaning you can only e-file these one by one on a PDF.  That's what they call it.

You can't prepare the PDF using your old software - that file won't be readable by FinCEN.  You have to download the fill-in PDF from FinCEN.  The website is not compatible with Chrome and Firefox somehow because of the version of Acrobat it requires, if I remember.  We ended up using either IE (or Edge - cant' recall exactly).

All the validation will be done at the time of submission, so you won't find out a day or two after the submission that it was rejected because your file contains illegal characters.  It's also very reliable in the sense that you will receive an acknowledgement almost instantaneously and the acceptance will come usually within 48 hours (whereas those filed through Intuit may not be accepted until after a week's time).