How to Create an Opacity Mask for Placed Image in Illustrator?
Make Opacity Mask with a Gradient in Adobe Illustrator CS6 - VisiHow
Opacity Mask Basics: Illustrator - Bittbox
PDF From Adobe Illustrator not showing a mask transparency right on macOS Preview or Windows? Here is the fix | Himmelberger Design - a Minneapolis, MN Web Design Company
Mastering Opacity Masks in Illustrator - The Shutterstock Blog
Illustrator Tip #33: Opacity Mask
How To Create A Transparent Gradient Mask with Illustrator
Solved: Opacity Mask not working - Illustrator Latest Upda... - Adobe Support Community - 11784357