This column can be edited, but the default is the end date of the Default Current Year and Default Current Term values entered on the Registration Configuration window. If you want to edit this column for one ID Number only, you can do so on the Student tab.
If you click the Create New Records button or Update Existing Records button, the process will use this year and term to verify that the student is registered. This will only be updated if a row exists in the STUDENT_TERM_SUM table for that same year and term and if TRANSACTION_STS is C or H for this ID Number.