Thanks PointC,
Thank you for your example, very helpful. I understand and apologize for the unnecessary complexity.
Questions:
The part that is to be masked is made up of smaller parts. Does each part of the group get ` mask="url(#svg-mask)" ` added?
Are the parts to be removed from group?
Thanks for the info on groups, I'd not found anything about that; very good to know. I'm testing the two questions above. Now the masked image does not appear at all.
Does each shape need its own <def> defined mask? Or can the same be applied to many elements?
The image complexity could be part of the problem here. I'll set about simplifying the image to make the work clearer. While it is not masking, and not the most elegant solution, I think it might work to add a 'cover' shape positioned to cover the group when outside the circle. I'd 'flunk' GSAP school if I implement that technique.
--Greg