This is CMS TAR version 2. (Yes, there was a CMS TAR version 1.)
CMS TAR version 2 is a from-scratch 'tar' creator/extractor built upon the powerful CMS Pipelines. Files archived with CMS TAR version 2 can be extracted UNIX 'tar' and files archived with UNIX 'tar' can be extracted with CMS TAR.
Also included is a TARLIST EXEC, a tool which allows you to browse a TAR archive and selectively view or extract files.
Feature note: this release of CMS TAR does not follow SFS hierarchies.