Sending a non-existent/not-defined signal

Hi all:

A quick question: I'm developing a GTK application, which, by default, 
defines a DBus service with several standard interfaces, which include 
the "org.gtk.Actions" interface. For several reasons I need to notify 
another program using DBus and a signal, and I found that I can use 
"emit_signal()" over a DBus object in my standard service/object to send 
a "random signal" (this is, a signal whose name isn't defined in any 
interface of that DBus object).

Although it does work, I'm afraid that it isn't very "legal", so my 
question is: is that something "allowable"? Or is that just a side 
effect of the current implementation, and could fail in other 
implementations, so I shouldn't do it?

Thanks.