A Meta-object Protocol is used in different object-oriented systems to specify behavior of the underlying object system [L1 ] [that link is not available 2009-May-14].
Different object-oriented languages have different meta-object protocols.
A meta-object protocol can also be used in applications where reflection is needed for a system to be able to examine itself
The term, reflection, is similar in meaning to Introspection.
See also TIP #117 [L12 ].
So, what does this have to do with Tcl?
Well, it really has to do with what features of a meta-object protocol are built into Tcl by itself, and what features are added by each of the object-oriented extensions.
escargo 25 Nov 2002
Also, the inclusion of a meta-object protocol can be the foundation of object-oriented extensions. I think of TIP 279 [L13 ] as defining a MOP to build OOP.
escargo 3 No 2006