basho/riak-php-client — comment on commit 10936481d6cf67b508465a24a3cc78e0c23d5a7d
File: riak.php line 1187
By intel352:

Anywhere in phpdoc that a parameter is being marked as "optional", it actually needs to come after the parameter, but before the description.
i.e. - @param string|int $explicitValue optional If provided, uses this...

You can see this explained in the docs for phpdoc, at the "function3" example: http://manual.phpdoc.org/HTMLSmartyConverter/HandS/phpDocumentor/tutorial_tags.param.pkg.html