What is !ADLINENYC

It's the "NYSE Common Stock Only Advance-Decline Line".

You can see the chart by putting the symbol in the window next to the "Sharpcharts" drop down at the top of your dashboard page.

Also, here's a link to a John Murphy blog article about it (from a Google search):

https://stockcharts.com/articles/chartwatchers/2016/05/two-versions-of-the-new-york-advance-decline-line-giving-different-signals.html