May I use the packet annotation?

[Jiangbo Li]

In Eddie Kohler's Thesis, it is said that " Annotations are
stored in the packet header in a fixed static order; there is
currently no way to dynamically add a new kind of annotation"

Is this mean no one can use the packet annotation except the 
click developers? I just want to make sure.
 
Annotation is really a good way to let elements communicate
each other.

We may add another information element, called AnnoInfo. And let
this element manage the freely avaliable annotations.

for example:
Annoinfo(myanno1,2)  // I need a 2 bytes annotation.
Annoinfo(myanno2,2)

...->MyElt1(myanno1)->MyElt2(myanno2)->MyElt3(myanno1)->MyElt4(myanno2)->...
In this case myanno1 and myanno2 should use the different 2 bytes
 in the packet annotation.

...->MyElt1(myanno1)->MyElt2(myanno1)->MyElt3(myanno2)->MyElt4(myanno2)->...
In this case myanno1 and myanno2 may use the same 2 bytes.


Is this doable? Acctually this may increase the difficulty of writing a 
router configuration. 

Thanks

Jiangbo Li