




 
Each COM interface pointer has a reference count which is used by the server to control its lifetime. The function 
release
 should be called whenever a reference to the interface pointer is being removed. The function invokes the COM method 
IUnknown::Release
 so the form 
(release ptr)
 is equivalent to using 
call-com-interface
 as follows:
(call-com-interface (ptr i-unknown release))