Q. What is 'reserve a DOI'? How will it be useful for me?

In a draft record, clicking on 'Reserve Digital Object Identifier' creates a DOI that is inactive and reserved for your item. It will only become active when you publish the record in SMU RDR. 

You can include the reserved DOI in a paper or provide it to the publisher without having to publish the dataset. You can publish the record or make your data open when you are ready to do so.