Example of White and Pure White Auto-Generation:Below is an example of an image with CMYK inks, along with pure white text. The image was saved as a PNG with a transparent background.
Using an auto-generation selection of "Auto Generate From Transparency Channel", with a density of 30% set for anywhere there is no transparency and a density of 75% for any area of "pure white".

A large choke was also applied, however, "Suppress Trapping on Pure Channel (White)" is active so there will be no choke applied to areas of "pure white".

The output of the white, using the above settings, will be the following: