Sweepstakes Directory
When the entry frequency is unknown the sweepstakes is listed in the "One Time" frequency category. This helps to ensure that it is not entered more times than is allowed.
When the expiration date is not found, it will be listed as "Unknown" in the directory.
Some sites have ongoing sweepstakes that are continuously running. When you see an expiration date of "Ongoing" for a sweepstakes it is one of these.