This plugin integrated with the plugin Edit Flow to support Pre-publication statuses replacing the WorkFlow_State taxonomy of the plugin.

The presence of that plugin is detected automatically and checks that the custom statuses have been activated for the document post type but the integration can be turned off by using the filter document_revisions_use_edit_flow even if the post type is set to use these statuses.

EditFlow was forked to become PublishPress and the plugin updated in Version 3.3 to be able to integrate with PublishPress by detecting that it was installed and looking in a different location for the statuses.

The same filter is used since Edit Flow and PublishPress are mutually incompatible.

Over time, PublishPress has been renamed to PublishPress Planner and a new plugin PublishPress Statuses released.

WP Document Revisions should be upgraded to support PublishPress Statuses in exactly the same way as it does for Edit Flow and PublishPress.