Continuous duty overnights (CDOs) are also referred to as "stand-ups", "naps", or "high-speeds" is a scheduling practice used in regional airline operations to circumvent, or "outsmart" government flight crew minimum rest requirements.
A crew working a CDO will generally operate the last flight out at night, have on duty time on the ground (anywhere from 0–8 hours) at the destination and then operate the first flight back in the morning.
Since the break between flights is not sufficient to qualify as a free from duty rest period, the crewmembers remain continuously on duty, even though they may have been provided with a hotel room for rest.
Crew members would normally require a specific amount of resting hours in between shifts based on their countries and airlines but by using the term continuous duty, they are able to go beyond the specified rest period due to being on duty.
The continuous duty overnight schedule could be flown 3–5 times consecutively (i.e., back-to-back).