The three files are:
Each of the /data subdirectories contain one or more of the following files:
table.directory. An XDR encoded file containing the data that was present in an NIS+ table at the time the backup was performed and also any data contained in any associated NIS+ log files. If there is an NIS+ table in the NIS+ directory object being backed up, a corresponding table.directory backup file will be created in the /data subdirectory for that directory object.
For example, every NIS+ org_dir directory contains a hosts table so there will be a hosts.org_dir file in each target/org_dir.domain/data subdirectory. For example, /master1_bakup/org_dir.doc.com./data/hosts.org_dir
User-created NIS+ tables present in a given directory object are backed up in the same way as the standard NIS+ tables.
groups_dir. An XDR encoded file containing NIS+ groups information. This file is stored in the corresponding NIS+ groups_dir target directory.