Out of gamut warnings have no well defined meaning using Perceptual Intent because all possible colors are supposed to be mapped to printable colors and compressed near the gamut boundaries. Ideally, the profile Perceptual tables can invert the printed color values to produce the originals.

Out of Gamut warnings are meaningful with Relative and Absolute Colorimetric intents because the specified color is printed so long as it is in gamut. If it isn't, the nearest printable color (usually based on delta E) gets printed. The Relative Col. tables in the profile then report back to the application the actual color printed. At least within profile, instrument and printer variance. When this actual differs from the requested color by an amount determined by the application, it may activate out of gamut masking or flagging.

However, How Perceptual tables in profiles are constructed is left to the profile designer and there are some major differences amongst printer OEMs. Canon normally does not perfectly invert Perceptual tables but instead, reports back the colorimetric value printed. Most other OEMs and profile software makers invert perceptual tables along the neutral axis.

As an example, Canon profile Perceptual tables can report back a L* value of 17 when an RGB value of 0,0,0 (black) is requested while a profile made by X-Rite or another paper supplier will almost certainly report back an L* of 0. Both actually print with a black at L*=17 in this example.

When printing using Relative Colorimetric, there is much more consistency between profiles from different vendors.