Open time. There is a column labeled "SLV". If it is blank, it is a regular open time trip. If there is an "N", that means the trip is a silver slip trip, but it is not yet biddable because it's in the 48 hour dwell period. If there is a "Y", that means the 48 hours is over, and it is awardable.

Silver trips can only be awarded via a silver slip. They cannot be white slipped unless they are returned to regular open time. Once they hit two days prior, they revert to normal trips and get covered via the coverage ladder.

All covered in the scheduling alert.