I'm working on scheme in Rebol3 and I'd like to add APPEND action. However, adding APPEND actor to the scheme does nothing, result of append my-scheme://localhost foobar is my-scheme://localhostfoobar instead of my action. The documentation is bit unfinished in this regard.
You need to use append on the port, and not the url!
port: open my-scheme://localhost
append port "my data"
The only port actors that can take a URL as an argument are those that have a port! specified as an argument. These are create, delete, open, close, read, write, open?, query, update, and rename. See http://www.rebol.net/wiki/Schemes:Notes#Port_Actions