XMI24 — Section 6.4.1 5j:Extension

I have a question regarding XMI 2.1 specification, document formal/05-09-01
I'm not certain that you are the right people to answer, but I'll try.

Here it is.

Section 6.4.1. Overall document structure (in EBNF rules production)
refers to 5j:Extension, however this element is never mentioned in the document. It was defined in XMI 2.0 formal/05-05-01.

Here is the fragment:

1a:XMI ::= "<" 1b:XMINamespace .....
...
( 5j:Extension )*
...

Is this an error in the document, or should we use the 5j:Extension from XMI 2.0 ?

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