From MdsWiki

A bug was introduced in version 1.8.1 which caused the on/off state to be changed to on for all nodes in a tree when the tree was cleaned or compressed. This bug should be fixed in this release. It is recommended that you upgrade to this version if you currently have version 1.8.1 installed on your system.

A new feature was also added in this release of MDSplus. The concept of data versions is now available. This new feature has not been heavily tested so be cautious before enabling versions on production systems.