When someone bubbles in their ID (such as a student ID) in a number grid, if they forget to do it, or if they do it incorrectly, is there a way to flag it with an error so I can fix it up later?

Yes. In version 1.4.6, the new aggregation rule system will allow you to send a form to unidentified images (in the processing queue part of the program) if the aggregation rule condition is met. For instance, you can use the following rule to send a form that does not have an ID of 6 characters in length to unidentified images for later reprocessing: !!!strleneq(6)!!?!!error!! - this rule reads - if the string length is not equal to 6, error the form. This is one of the most common problems people have when scanning forms where students have to bubble in their identification information, and can greatly help automate the process of fixing this issue.