Generation Resources submit their GADS data into the MISO PowerGADS database through the MISO Market Portal on a quarterly basis.  The deadline to submit is 30 days after the end of the quarter.  For example, the first quarter data from January 1 through March 31 is due by April 30.  The data is locked from editing once the deadline has passed. 
When you try to revise GADS data that is in a period that has been locked you receive the card lock error message that “(Unit) is locked for the selected date.” 
To request that MISO unlock your unit send an email to  The email should include the utility and unit numbers and a brief explanation for the revision.
More information on GADS Reporting can be found in the Resource Adequacy Business Practices Manual (BPM-011) and in the North American Electric Reliability Corporation (NERC) Data Reporting Instructions.