There is also a new amendment 33A to ICAO annex 6, effective july 2009. It is a recommendation:
4.4.10 Aeroplane operating procedures for rates of climb and descent
Recommendation.— Unless otherwise specified in an air traffic control instruction, to avoid unnecessary airborne collision avoidance system (ACAS II) resolution advisories in aircraft at or approaching adjacent altitudes or flight levels, operators should specify procedures by which an aeroplane
climbing or descending to an assigned altitude or flight level, especially with an autopilot engaged, may do so at a rate less than 8 m/sec or 1 500 ft/min (depending on the instrumentation available) throughout the last 300 m (1 000 ft) of climb or descent to the assigned level when the pilot is made aware
of another aircraft at or approaching an adjacent altitude or flight level.