ICAO Doc 8168
4.3 OMNIDIRECTIONAL DEPARTURES
4.3.1 Omnidirectional departures normally allow departures in any direction. Restrictions are expressed as:

a) sectors to be avoided; or
b) sectors having minimum gradients and/or minimum altitudes.

4.3.2 Sectors are described by bearings and distance from the centre of Area 3.

4.3.3 When more than one sector is involved, the published minimum gradient will be the highest of any sector that may be expected to be overflown.

4.3.4 The altitude to which the minimum gradient is specified will permit the aircraft to continue at the 3.3 per cent (helicopters, 5 per cent) minimum gradient through that sector, a succeeding sector, or to an altitude authorized for another phase of flight (i.e. en-route, holding or approach). See Figure I-3-1-2 in Chapter 1 of this section.

4.3.5 A fix may also be designated to mark the point at which a gradient in excess of 3.3 per cent (helicopters, 5 per cent) is no longer required.