Both linear and non-linear visuals are present on the X11 screen visual list, which can be queried with XGetVisualInfo. Because linearity is not a visual property recognized by the X11 core protocol, an extended routine must be called to distinguish a linear visual from its nonlinear counterpart. This routine is XSolarisGetVisualGamma. Refer to the XSolarisGetVisualGamma(1) man page for further details.
CG14 does not have linear visuals like the Creator accelerator. It performs gamma correction using a special Gamma LUT that affects the entire screen. Thus, it is not possible on the CG14 to have both gamma-corrected and uncorrected 24-bit windows on the screen at the same time. This is possible, however, on the Creator accelerator.