Release 6.1.1 is a bug fix release, superseding 6.1.0.
Release 6.1.0 is a maintenance release, fixing all current bugs.
Release 6.0.1 is a bug fix release, superseding 6.0.0.
Release 6.0.0 is release 6 with and with only API and pathname changes so that it moves into the new namespace scheme. The code otherwise is completely unchanged.
Release 6 is the original liblfds prior to the new versioning scheme.