[lkramer]

This is interesting. I wonder why it's not visible by default.

[layer8]

Maybe it is/was an A/B test, to see if it hurts ad revenue (it probably does).

The option appeared randomly for me on a search, and I took immediately note of the udm number. :)

[wholinator2]

In addition to the others mentioned on the sibling comment (I cannot reply to it?), udm=28 is shopping, 36 is books, 37 is "products", 44 is "visual matches", 48 is "exact matches", 50 is "AI Mode" but no tab appears, 51 is homework and I stopped at 80 because the page kept removing that part of the url all the way up to that point.

[Scoundreller]

For some reason the reply button won’t pop up right away but you can click on the post’s timestamp and reply there

[Scoundreller]

Ran through the lower numbers that hit something interesting:

8 = jobs (but doesn't return any results) 15 = attractions (but doesn't return any results)