Much has been written about the RGBM (Reduced Gradient Bubbles Model) & the occurrence of microbubbles. Below is a (very) brief summary of what it means:

The Mares-Wienke RGBM (Reduced Gradient Bubbles Model) algorithm takes into account the phenomenon of micro-bubbles in order to prevent their formation to the greatest possible extent. In over 10,000 real dives monitored by Dr. Bruce Wienke in the Los Alamos laboratories, the formation of micro-bubbles has been studied and evaluated in order to better understand the mechanism behind how micro-bubbles are formed during a dive.Today it is the most evolved algorithm for reducing the formation of micro-bubbles without compromising dive times.

DEEP STOP

As a further result of the intensive research work done by Dr. Bruce Wienke, MARES (& others) and Dr. Wienke's team have added the deep-stop function to their dive computers. This function helps prevent the formation of micro-bubbles at greater depths during the diver's ascent to the surface. This model is widely used in the field of technical and commercial diving, where added safety is a must to ensure the health of divers who dive frequently under severe conditions. All these added safety features do not extend your total dive time, but they significantly increase your safety.

The Suunto D9 amongst others has the RGBM model installed & the user can select whether Deep Stop is active or not & how long the stop should be (typically one or two minutes is normal). If it is off, then an optional three minute safety stop commences once the diver reaches 6m, but cuts out if the diver ascends above 3m. It will resume provided the diver moves back into the 6m - 3m window within a given time. If the diver ignores the stop, there is no penalty - provided of course it is a safety stop (which is optional) & not a Decompression Stop (which is mandatory!).
If the Deep Stop is on, then half-pressure stops activate whilst the model thinks you need to do them. In reality, if a dive is to 20m or less, then Deep Stops are fairly pointless.

It is not possible to change this setting underwater so a decision needs to be made prior to the dive. For more information on this & other related planning, check out the Decompression Diving notes below.