There is a datasource setting that can be set by your administrator called Lock reference documents to versions, that controls the default behavior of how reference documents that have versions are attached to the master document.

• When off (the default), the master document will always use the active version of a reference.
• When on, and the user attaches a reference to a master, the reference is locked to the sequence number of the reference's active version. This way, as new versions of the reference are created and the active version's sequence number slides forward, the master document will always use a fixed version of the reference (specifically, the version which now has the sequence number that the active version had when the reference was originally attached).

Regardless of this datasource setting, in ProjectWise Explorer you can update a master document to use any version you like of a particular reference. The version that you specify will be copied out and used (instead of the active version) when the master document is opened. This version of the reference will continue to be used by the master document until or unless you select another version to lock to the master document. You can also set it so that the active version of the reference document is always the version that is used by the master document.