TCP/UDP binding: How to send String or Number Item?

Hello together,

I want to use the UDP binding to send a string from OpenHAB (UDP client) to another network device which runs an UDP server.
It works perfectly fine for a switch item:

 Switch Light_Test "Test"  (Lights)   { udp=">[ON:'MAP('], >[OFF:'MAP(']" }

I also want to send some other information to the UDP server like the current outdoor temerature which I am getting via KNX.
But how do I achieve this? What is the syntax to do this, i.e. what is the “command” and how do I reference the string/number in the “transformationrule”?
Tried the following, but it failed as I expected :frowning:

Number Weather_Temperature  "Aussentemperatur [%.1f °C]"   <temperature>   (Weather_Chart, Temperature)   { knx="<9.001:0/7/0", udp=">[] }

Thanks & Regards,