SPTD stands for SCSI Pass Through Direct layer. Basically SPTD is similar to other access layers used by other programs who provide access to storage devices but it has a lot more features that make this interface unique.
SPTD EULA:
http://www.duplexsecure.com/download/SPTD-156.rtf
Issues addressed:
- Fixed some incompatibility issues;
- Fixed system deadlock on multi-processor environment;
- Fixed some minor bugs.