I did read, yes. But some parts of the documentation and Webhook widget naming/hints threw me off.
Widget/OUTPUT: I can put here any virtual pin; even a virtual pin which doesn’t get updated. For example: I put here V12, but my Arduino device never writes anything to V12, and yet webhook gets triggered. Also, this V12 value isn’t sent anywhere, even though the name “output” suggests to me it does.
Widget/URL: For example in case of Thingspeak I would write here …&field1=/pin/&field2=/pin/… and so on. But pin actually refers to virtual in V1 and so on, and not to V0 as the name seems to suggest.
But I think I have understood it now and I can attack the real problem which is how to send data to external mySQL database. I’m able to send text to mySQL. But have not been successful yet to send value stored in virtual pin.