Revisions Checkin Options
Always update database structure when doing a checkin
If checked, before checking in, the PDM opens the checked-out document, update it’s structure in the database, update the custom properties and saves it again.
This option is fundamental when acting with checkedout documents and when the other option Open/Save→Save→
Always update database structure on checked-out documents save is disabled;
In such case the PDM never updates the database structure and records unless you explicitly click Shift + the button refresh 
in the toolbar.
Please note that for performance issues, this option updates the top most assembly first level only, rather than all its below whole structure.
In case you need to update the whole db structure (rather than 1st level only) we suggest to enable the OnCheckoutCheckinApproveTree.lst script (see the example in the specific script page).
Always update database structure when undoing a checkin
If checked, before undoing a checkin MechworksPDM opens the released document, update it’s structure in the database, update the custom properties and saves it again. This reverts to the same situation of the document as when it was released. Of course, most of the times the structure hasn't been modified, making this operation unnecessary.
Exclude Parts (and related Drawings) from the update
When checked, and at least one of 
Always update database structure when doing a checkin or Always update database structure when undoing a check-in option being activated, the Part Models (and their related Drawings) will not be opened in memory for updating their database structure.
Also all the other database properties that can be calculated only when the models are opened in memory (like Material, etc.) will not be updated.
The intent of this option is to improve the performance of the checkin of very large assemblies, when, since of a specific company workflow, the parts will never need a refresh by opening them in memory before checking them in.
It's strongly suggested to to carefully manage this option and to explore all the possible side effects before putting it into production.
Always calculate mass properties when doing a checkin
If checked, each time you finish working on a part or assembly and check it back in, DBWorks recalculates mass properties in case you changed the geometry of the document. This option can be time consuming as it inhibits the optimization of assembly structure updating.
Calculate mass properties only for Parts
self explanatory
Calculate only Length and Dimensions
Related to the same option in section Open/Save→Save
Mark as 'dirty' any Parent Document on Checkin
This option is enabled only when the option Revision→Approval→Mark as 'dirty' a parent revision on a child new revision approval is checked.
When checked, on a Checkin, or when a new Revision is created, any Parent Document is marked with DIRTY_REVISION_FLAG=1 and displayed as 'dirty' Document in the User Interface.
Once a Parent Document is marked as dirty, it will stay dirty until a state change (i.e. checkout or new revision) will be applied to the Parent Document itself The DIRTY_REVISION_FLAG of the Parent Document is NOT cleaned when unchecking-in the Child Document that has invalidated it
Send notification to all users on check-in
If checked ( default ), DBWorks always sends a RELOAD COMPONENT message on the check-in of a document.
The users that currently have the component loaded in memory will see a message box on their desktops saying that the component has been modified.
Notify silently any update of in-memory read-only documents
When checked, DBWorks will never popup any notification dialog when an in-memory read-only component has been modified by another designer.
Only a tooltip will appear on the screen for remembering that a component needs to be reloaded.
The DBWorks Toolbar Reload button 
will become enabled, and it will be possible to reload all the notified components at any time.