Indeed. I'll add support for strong and weak.

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Strong and weak is working but unsafe_unretained is still documented as retain.

I couldn't find anything about it in the official docs, but I'll add it.

You can find it here https://developer.apple.com/library/mac/#releasenotes/ObjectiveC/RN-TransitioningToARC/Introduction/Introduction.html
it is used on iOS4 and  (OS X 10.6 i think)  because they doesn't support weak references.

I nowhere see it as being part of a property attribute, like so:

@property (nonatomic, unsafe_unretained) NSNumber *yearOfBirth;

but I read somewhere that unsafe_unretained is defined as an alias for assign.

Sorry the wrong documentation. Here you find it in section 4.1.1

http://clang.llvm.org/docs/AutomaticReferenceCounting.html 

It's right unsafe_unretained and weak is like an alias for assign. 
The difference between unsafe_unretained and weak is that 
weak properties get nil when the object they store is released. 
Unsafe_unretained properties remain as a dangling pointer.

This bug was previously marked ASSIGNED, which means it should be fixed in
doxygen version 1.8.1.2. Please verify if this is indeed the case. Reopen the
bug if you think it is not fixed and please include any additional information
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