Unfamiliar with this syntax. Any help?

I have tried searching for an answer to this, but I really don't know what kind of search strings will get me the results that I need.

I'm working on a PHP file that another person at my company coded. This person no longer works here so I can't ask him about it.

Here is the code:

<?=$metaTags;?>

Code (markup):

I have a strictly HTML file, and then this code is in the 'head' tag. It basically prints the meta tags for that particular page.

I know what it does, but I have never seen syntax like this. It seems to me that it should be invalid PHP code. However, this

<?php=$metaTags;?>

Code (markup):

throws an error.

Does anyone know where I can learn more about this syntax, and its use?

 

It's short hand for

<?php echo $metaTags; ?>

PHP:

 

Thanks! Do you know where I can read up on this shorthand method as well as any others?