What I found on this topic:

- http://stackoverflow.com/questions/4995753/phpdoc-whats-the-proper-way-to-document-a-constant
- https://github.com/phpDocumentor/phpDocumentor2/issues/247
- http://stackoverflow.com/questions/6706051/phpdoc-for-constants
- http://www.phpdoc.de/kongress/constant.html

From these sources I came to the conslusion that the `@type` annotation is best for the constants.

What do you think?