What happened to -undercolor (CMYK black generation) ???

[lsm]

What happened to the functionality formerly known as "-undercolor" in older versions of ImageMagick? (actually, it looks like imagemagick, with convert, mogrify, etc., and a virtually identical command line approach and structure, but web searches are 10 years old and show ownership by E.I. du Pont de Nemours and Company Incorporated???)

-undercolor <undercolor factor>x<black-generation factor>
control undercolor removal and black generation on CMYK images.

This option enables you to perform undercolor removal and black generation on CMYK images-- images to be printed on a four-color printing system. You can con- trol how much cyan, magenta, and yellow to remove from your image and how much black to add to it. The stan- dard undercolor removal is 1.0x1.0. You'll frequently get better results, though, if the percentage of black you add to your image is slightly higher than the per- centage of C, M, and Y you remove from it. For example you might try 0.5x0.7.

[magick]

Undercolor removal and black generation has not been supported in ImageMagick for over 10 years.