It was first used in 2008 to discern the new Edge Zero-equipped models from its similar but Edge Pro-equipped 2007 counterparts, for example the RGT320Q and RGT320Z. Ibanez has used the suffix consistently until 2010, even with models that did not exist before the introduction of the Edge Zero.
In 2010, the last Edge Pro models were replaced by new Edge Zero models. Again, the Edge Zero-equipped models got new model names, such as the RG1570Z and RG1527Z. In the USA however, Ibanez kept on promoting the Edge Pro-equipped models along with the new models and both were listed without the Z suffix, allowing for a smoother transition. As of 2011, Ibanez still lists these models without the Z suffix. For instance, both the original RG1550M and the Edge Zero-equipped RG1550MZ are known as the RG1550M in the USA.
The Z suffix is also used for models with the Edge Zero II tremolo for similar reasons. Both models previously equipped with the Edge III tremolo and completely new models have model names with the Z prefix, such as the RG350DXZ and the RG870QMZ. Often in US promotional material, the Z prefix for the Edge Zero II tremolo is ignored completely. For example, the RG370DXZ and RG370DX are both referred to as the RG350DX and the new RG870Z is known as simply the RG870 in the USA.