G7 is both a definition of greyscale appearance, and a calibration method. The G7 calibration method uses the G7 definition to grey balance the output colours of the printer. A good grey balance is important because the human eye is very sensitive to subtle changes in greys.
PRISMAsync supports the use of G7 calibration curves created by external tooling. However, PRISMsync also offers a very easy and quick way to create G7 output profiles and calibration curves with feedback about the output profiles and calibration process. (Perform a G7 media family calibration)
In addition you can perform a G7 greyscale verification procedure. The feedback of this procedure shows immediately that your printed output meets the G7 standard. (Perform the G7 greyscale verification procedure)
G7 Legacy CMY requires that 300% CMY must be neutral (a* = 0 and b* = 0). This requirement does not always provide the most optimal grey values when using a printer. Hence, printers use G7 Native CMY to achieve G7 compliance. With G7 Native CMY the target a* and b* values for CMY grey levels are gradually adjusted along a curve that ends at the native a* and b* values of the printer's 300% CMY level. (Learn about colour differences and tolerances)