Phpword $ objWriter属性

I am using PHPWord in a project.

I am trying to find out some information about the attributes that go with the $objWriter:

$objWriter = \PhpOffice\PhpWord\IOFactory::createWriter($phpWord, 'Word2007');

Specifically, what is the 'Word2007' used for at the end? I have tried searching $objWriter but can't locate any info. I have tried replacing it with 'Word2013' or 'Word2016' but I get:

"Word2016" is not a valid writer. in wamp...\vendor\phpoffice\phpword\src\PhpWord\IOFactory.php on line 29

The 2nd parameter is for the type of document you're creating a writer for. There are 5 allowed types:

1. 'ODText'
2. 'RTF'
3. 'Word2007'
4. 'HTML'
5. 'PDF'

You can see this in the code for the IOFactory class:

public static function createWriter(PhpWord $phpWord, $name = 'Word2007')
{
    /**
     * Notice the allowed names in the array here.
     */
    if ($name !== 'WriterInterface' && !in_array($name, array('ODText', 'RTF', 'Word2007', 'HTML', 'PDF'), true)) {
        throw new Exception("\"{$name}\" is not a valid writer.");
    }
    $fqName = "PhpOffice\\PhpWord\\Writer\\{$name}";
    return new $fqName($phpWord);
}

https://github.com/PHPOffice/PHPWord/blob/develop/src/PhpWord/IOFactory.php

If you want to support a later MS Word document format, you will need to implement your own writer that extends AbstractWriter implements WriterInterface. However, at this time, there are no later formats yet created. (Note that Word 2007 the format is different from the application version.)