Non-revs traveling on company business (NRPS) when standing by for a different flight than booked, or when not able to confirm an E class booking to begin with, may trump some types of revenue standbys. Both non-elite non-full-fare revenue and NRPS standbys will have priority status of "DRX" on the standby list but the list is automatically sorted in such a way that NRPS DRXs do come before revenue ones.

Again though just to clarify this only applies to non-revs standing by while traveling on official company business. This does not apply to leisure standby NRSA travel which will be lower down on the priority list (codes D1, D2, D3).