Great question. ;)
A title commitment is marked up by the title agent when they have completed the transaction and are prepping the file notes for the issuance of the title policy.
The mark up takes place during the closing process and is therefore not available prior to closing.
If you are given a marked up title commitment prior to closing it isn't a genuine mark up.
Consumers and lenders should always review their title commitment prior to closing. The availability of the title commitment is tied to how quickly folks want to close after the commitment is produced. Make sure your title agent knows that you expect to review the title commitment prior to the closing and let them know you want that copy as soon as the commitment is issued.
The marking of the title commitment is a review of the commitment to make sure all conditions listed on Schedule B1 are cleared. It is also a final check of endorsements to be issued as requested by the lender and all other policy terms will be checked.
You can ask for a copy of the marked up title commitment AFTER closing or AT closing. That's an unusual request so let the title agent know you want it. I think it's overkill unless your review of the title commitment noted a matter that you wanted changed. In that case, getting a copy of the marked up commitment would confirm for you that the title agent made the requested change and if you are being such a diligent consumer, I say HOORAY! ;)