@Hal_Al
I was relying on this.
web page:
https://taxfoundation.org/remote-work-from-home-teleworking/
or download PDF:
https://files.taxfoundation.org/20200812115626/Teleworking-Employees-Face-Double-Taxation-Due-to-Agg...
"Six states—Arkansas, Connecticut, Delaware, Nebraska, New York, and Pennsylvania—had implemented so-called convenience rules prior to the COVID-19 pandemic, while Massachusetts adopted a temporary income sourcing rule with the same effect in response to pandemic-era telework."
But it does not go into any detail. Your reference is both more recent and more authoritative.
