RADB route object "advisory" field

hi, this is substantially different from the usual threads i see on this list, and i trust someone will let me know if it's completely inappropriate. can anyone more experienced with the RADB than i (that's probably most everyone here) point me to documentation describing the "advisory" field in RADB route objects? i've looked through the docs at www.ra.net and found no mention of this field. thanks, ken