A "header", in phpDocumentor 1, is the thing between ```/**``` and the short description, used in [DocBlock templates](http://manual.phpdoc.org/HTMLSmartyConverter/PHP/phpDocumentor/tutorial_phpDocumentor.howto.pkg.html#basics.docblocktemplate). There's no "header description" per se, but since there IS such a thing as a "header", mixing terms like that can be confusing.


In this particular case, that line appears to be used to describe syntactically the fact that one can have the short description outside the ```@var``` description, as well as within it (as the above lines show).