>>An object will not be released as long as at least one reference to it exists. Storing reference to the parameter object in a property of the child form guaranteed that it'll be available as long as form exists.
>
>On testing, that seems to be true. However, I for one have never relied on that feature, I haven't seen it documented anywhere. You can end up with code that does not act as "expected", but throws no errors:
>

>CLEAR
>
>loParameter = CREATEOBJECT( "Custom" )
>loParameter.AddProperty( "MyString", "Hello World" )
>
>loMyChild = CREATEOBJECT( "MyChild", loParameter )
>
>loParameter.MyString = "Hello World 2"
>loMyChild.MyPrint( )
>
>* Section below does not throw any error
>* even though loParameter is not actually released
>loParameter.MyString = "Hello World 3"
>RELEASE loParameter
>loParameter = .NULL.
>loMyChild.MyPrint( )
>
>RETURN
>
>DEFINE CLASS MyChild AS Custom
>	MyPORef = ""
>	
>	FUNCTION Init
>		LPARAMETERS toParameter
>		
>		This.MyPORef = toParameter
>		
>		=This.MyPrint( )
>	
>	ENDFUNC
>	
>	FUNCTION MyPrint
>		? This.MyPORef.MyString
>		
>	ENDFUNC
>
>ENDDEFINE
>

The interesting part is that this is as it should be, but it takes some thinking to understand why. The moment you released loParameter, the variable was gone. In the next line, you issue a loParameter=null, but that's a new private variable, completely unrelated to the previous one, and that line does practically nothing, as your loMyChild.MyPopRef is still a reference to the original one.

The part which introduces confusion is when you release a variable and then use it again - not something you would regularly do (we have the local scope for automatically releasing variables), and surely something that would (at least should) look suspicious to anyone reading the code.