I used "all objects" to mean the Jim_Obj objects in the C code I linked to, and int_19h used "object" for OO objects, but we are talking about the same kind of

I used "all objects" to mean the Jim_Obj objects in the C code I linked to, and int_19h used "object" for OO objects, but we are talking about the same kind of GC. int_19h's comment explains how implementing tracing garbage collection for OO object references without breaking EIAS would require a very pessimistic garbage collector. My reply is about how Jim Tcl implements this exact type of pessimistic tracing garbage collection for references, the basis of its OO system. I should have just said "all values". The name Tcl_Obj/Jim_Obj is a legacy artifact that leads to lots of confusion. Perhaps Tcl 9 will rename Tcl_Obj to Tcl_Value.