servname -a string containing the name of the server application as in "Excel"
topic - a string naming a topic for the server. Often a filename as in "VDDEEXT.XLS"
return value - returns a non negative channel id on success or -1 on failure. The returned channel id should be used in all subsequent calls to the vdde... functions.
The vdde_initiate function is used to begin a DDE conversation. This is normally called from the function simulation_setup. servname is usually the name of an application and topic the name of a file, but the actually meaning of the parameters depends upon the DDE server you are using.
